System for maintaining engine oil at a desired temperature

ABSTRACT

A temperature control system, in a liquid cooled internal combustion engine equipped with a radiator, controls the state of a flow control valve for controlling flow of a temperature control fluid through a passageway in the engine. Sensors detect the engine oil temperature and the temperature of the temperature control fluid. An engine computer receives signals from the sensors and compares the signals to one or more predetermined values. In one embodiment, the engine computer compares the engine oil temperature signal to a predetermined value to control actuation of the valve. In another embodiment, the engine computer compares the engine oil temperature signal to a predetermined engine oil temperature value. The engine computer adjusts a predetermined temperature control fluid temperature value based on the comparison of the engine oil temperature signal to the predetermined engine oil temperature value. The engine computer then compares the temperature control fluid temperature signal to the adjusted temperature control fluid temperature. The engine computer actuates the flow control valve based on the comparison of the temperature control fluid temperature signal to the adjusted temperature control fluid temperature.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a related to U.S. application Ser. No. 08/390,711,pending, filed Feb. 17, 1995 and entitled "SYSTEM FOR MAINTAINING ENGINEOIL AT AN OPTIMUM TEMPERATURE," which is a continuation-in-part of U.S.application Ser. No. 08/306,272 filed Sep. 14, 1994 and now U.S. Pat.No. 5,467,745 entitled "SYSTEM FOR DETERMINING THE APPROPRIATE STATE OFA FLOW CONTROL VALVE AND CONTROLLING ITS STATE." The entire disclosuresof both of these applications is incorporated herein by reference. Thisapplication is also related to U.S. application Ser. No. 08/469,957filed Jun. 6, 1995 and now U.S. Pat. No. 5,507,251 entitled "SYSTEM FORDETERMINING THE LOAD CONDITION OF AN ENGINE FOR MAINTAINING OPTIMUMENGINE OIL TEMPERATURE." The entire disclosure of this application isincorporated herein by reference.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a related to U.S. application Ser. No. 08/390,711,pending, filed Feb. 17, 1995 and entitled "SYSTEM FOR MAINTAINING ENGINEOIL AT AN OPTIMUM TEMPERATURE," which is a continuation-in-part of U.S.application Ser. No. 08/306,272 filed Sep. 14, 1994 and now U.S. Pat.No. 5,467,745 entitled "SYSTEM FOR DETERMINING THE APPROPRIATE STATE OFA FLOW CONTROL VALVE AND CONTROLLING ITS STATE." The entire disclosuresof both of these applications is incorporated herein by reference. Thisapplication is also related to U.S. application Ser. No. 08/469,957filed Jun. 6, 1995 and now U.S. Pat. No. 5,507,251 entitled "SYSTEM FORDETERMINING THE LOAD CONDITION OF AN ENGINE FOR MAINTAINING OPTIMUMENGINE OIL TEMPERATURE." The entire disclosure of this application isincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to a system for maintaining engine lubricationoil at a desired temperature by controlling the state of one or moreflow control valves which regulate the flow of temperature control fluidwithin an internal combustion gasoline or diesel engine equipped with aradiator.

BACKGROUND OF THE INVENTION

Page 169 of the Goodheart-Willcox Automotive Encyclopedia, TheGoodheart-Willcox Company, Inc., South Holland, Ill., 1995 describesthat as fuel is burned in an internal combustion engine, about one-thirdof the heat energy in the fuel is converted to power. Mother third goesout the exhaust pipe unused, and the remaining third must be handled bya cooling system. This third is often underestimated and even lessunderstood.

Most internal combustion engines employ a pressurized cooling system todissipate the heat energy generated by the combustion process. Thecooling system circulates water or liquid coolant through a water jacketwhich surrounds certain parts of the engine (e.g., block, cylinder,cylinder head, pistons). The heat energy is transferred from the engineparts to the coolant in the water jacket. In hot ambient air temperatureenvironments, or when the engine is working hard, the transferred heatenergy will be so great that it will cause the liquid coolant to boil(i.e., vaporize) and destroy the cooling system. To prevent this fromhappening, the hot coolant is circulated through a radiator well beforeit reaches its boiling point. The radiator dissipates enough of the heatenergy to the surrounding air to maintain the coolant in the liquidstate.

In cold ambient air temperature environments, especially below zerodegrees Fahrenheit, or when a cold engine is started, the coolant rarelybecomes hot enough to boil. Thus, the coolant does not need to flowthrough the radiator. Nor is it desirable to dissipate the heat energyin the coolant in such environments since internal combustion enginesoperate most efficiently and pollute the least when they are runningrelatively hot. A cold running engine will have significantly greatersliding friction between the pistons and respective cylinder walls thana hot running engine because oil viscosity decreases with temperature. Acold running engine will also have less complete combustion in theengine combustion chamber and will build up sludge more rapidly than ahot running engine. In an attempt to increase the combustion when theengine is cold, a richer fuel is provided. All of these factors lowerfuel economy and increase levels of hydrocarbon exhaust emissions.

To avoid running the coolant through the radiator, coolant systemsemploy a thermostat. The thermostat operates as a one-way valve,blocking or allowing flow to the radiator. FIGS. 40-42 (described below)and FIG. 2 of U.S. Pat. No. 4,545,333 show typical prior art thermostatcontrolled coolant systems. Most prior art coolant systems employ waxpellet type or bimetallic coil type thermostats. These thermostats areself-contained devices which open and close according to precalibratedtemperature values.

Coolant systems must perform a plurality of functions, in addition tocooling the engine parts. In cold weather, the cooling system mustdeliver hot coolant to heat exchangers associated with the heating anddefrosting system so that the heater and defroster can deliver warm airto the passenger compartment and windows. The coolant system must alsodeliver hot coolant to the intake manifold to heat incoming air destinedfor combustion, especially in cold ambient air temperature environments,or when a cold engine is started. Ideally, the coolant system shouldalso reduce its volume and speed of flow when the engine parts are coldso as to allow the engine to reach an optimum hot operating temperature.Since one or both of the intake manifold and heater need hot coolant incold ambient air temperatures and/or during engine start-up, it is notpractical to completely shut off the coolant flow through the engineblock.

Practical design constraints limit the ability of the coolant system toadapt to a wide range of operating environments. For example, the heatremoving capacity is limited by the size of the radiator and the volumeand speed of coolant flow. The state of the self-contained prior art waxpellet type or bimetallic coil type thermostats is controlled solely bycoolant temperature. Thus, other factors such as ambient air temperaturecannot be taken into account when setting the state of such thermostats.

Numerous proposals have been set forth in the prior art to morecarefully tailor the coolant system to the needs of the vehicle and toimprove upon the relatively inflexible prior art thermostats.

U.S. Pat. No. 4,484,541 discloses a vacuum operated diaphragm type flowcontrol valve which replaces a prior art thermostat valve in an enginecooling system. When the coolant temperature is in a predeterminedrange, the state of the diaphragm valve is controlled in response to theintake manifold vacuum. This allows the engine coolant system to respondmore closely to the actual load on the engine. U.S. Pat. No. 4,484,541also discloses in FIG. 4 a system for blocking all coolant flow througha bypass passage when the diaphragm valve allows coolant flow into theradiator. In this manner, all of the coolant circulates through theradiator (i.e., none is diverted through the bypass passage), therebyshortening the cooling time.

U.S. Pat. No. 4,399,775 discloses a vacuum operated diaphragm valve foropening and closing a bypass for bypassing a wax pellet type thermostatvalve. During light engine load operation, the diaphragm valve closesthe bypass so that coolant flow to the radiator is controlled by the waxpellet type thermostat. During heavy engine load operation, thediaphragm valve opens the bypass, thereby removing the thermostat fromthe coolant flow path. Bypassing the thermostat increases the volume ofcooling water flowing to the radiator, thereby increasing the thermalefficiency of the engine.

U.S. Pat. No. 4,399,776 discloses a solenoid actuated flow control valvefor preventing coolant from circulating in the engine body in coldengine operation, thereby accelerating engine warm-up. This patent alsoemploys a conventional thermostat valve.

U.S. Pat. No. 4,545,333 discloses a vacuum actuated diaphragm flowcontrol valve for replacing a conventional thermostat valve. The flowcontrol valve is computer controlled according to sensed engineparameters.

U.S. Pat. No. 4,369,738 discloses a radiator flow regulation valve and ablock transfer flow regulation valve which replace the function of theprior art thermostat valve. Both of those valves receive electricalcontrol signals from a controller. The valves may be either vacuumactuated diaphragm valves or may be directly actuated by linear motors,solenoids or the like. In one embodiment of the invention disclosed inthis patent, the controller varies the opening amount of the radiatorflow regulation valve in accordance with a block output fluidtemperature.

U.S. Pat. No. 5,121,714 discloses a system for directing coolant intothe engine in two different streams when the oil temperature is above apredetermined value. One stream flows through the cylinder head and theother stream flows through the cylinder block. When the oil temperatureis below the predetermined value, a flow control valve closes off thestream through the cylinder block. Although this patent suggests thatthe flow control valve can be hydraulically actuated, no specificexamples are disclosed. The flow control valve is connected to anelectronic control unit (ECU). This patent describes that the ECUreceives signals from an outside air temperature sensor, an intake airtemperature sensor, an intake pipe vacuum pressure sensor, a vehiclevelocity sensor, an engine rotation sensor and an oil temperaturesensor. The ECU calculates the best operating conditions of the enginecooling system and sends control signals to the flow control valve andto other engine cooling system components.

U.S. Pat. No. 5,121,714 employs a typical prior art thermostat valve 108for directing the cooling fluid through a radiator when its temperatureis above a preselected value. This patent also describes that thethermostat valve can be replaced by an electrical-control valve,although no specific examples are disclosed.

U.S. Pat. No. 4,744,336 discloses a solenoid actuated piston type flowcontrol valve for infinitely varying coolant flow into a servocontrolled valve. The solenoids receive pulse signals from an electroniccontrol unit (ECU). The ECU receives inputs from sensors measuringambient temperature, engine input and output coolant temperature,combustion temperature, manifold pressure and heater temperature.

One prior art method for tailoring the cooling needs of an engine to theactual engine operating conditions is to selectively cool differentportions of an engine block by directing coolant through differentcooling jackets (i.e., multiple circuit cooling systems). Typically, onecooling jacket is associated with the engine cylinder head and anothercooling jacket is associated with the cylinder block.

For example, U.S. Pat. No. 4,539,942 employs a single cooling fluid pumpand a plurality of flow control valves to selectively direct the coolantthrough the respective portions of the engine block. U.S. Pat. No.4,423,705 shows in FIGS. 4 and 5 a system which employs a single waterpump and a flow divider valve for directing cooling water to head andblock portions of the engine.

Other prior art systems employ two separate water pumps, one for eachjacket. Examples of these systems are given in U.S. Pat. No. 4,423,705(see FIG. 1), U.S. Pat. No. 4,726,324, U.S. Pat. No. 4,726,325 and U.S.Pat. No. 4,369,738.

Still other prior art systems employ a single water pump and singlewater jacket, and vary the flow rate of the coolant by varying the speedof the water pump.

U.S. Pat. No. 5,121,714 discloses a water pump which is driven by an oilhydraulic motor. The oil hydraulic motor is connected to an oilhydraulic pump which is driven by the engine through a clutch. Anelectronic control unit (ECU) varies the discharge volume of the waterpump according to selected engine parameters.

U.S. Pat. No. 4,079,715 discloses an electromagnetic clutch fordisengaging a water pump from its drive means during engine start-up orwhen the engine coolant temperature is below a predetermined level.

Published application nos. JP 55-35167 and JP 53-136144 (described incolumn 1, lines 30-62 of U.S. Pat. No. 4,423,705) disclose clutchesassociated with the driving mechanism of a water pump so that the pumpcan be stopped under cold engine operation or when the cooling watertemperature is below a predetermined value.

The goal of all engine cooling systems is to maintain the internalengine temperature as close as possible to a predetermined optimumvalue. Since engine coolant temperature generally tracks internal enginetemperature, the prior art approach to controlling internal enginetemperature control is to control engine coolant temperature. Manyproblems arise from this approach. For example, sudden load increases onan engine may cause the internal engine temperature to significantlyexceed the optimum value before the coolant temperature reflects thisfact. If the thermostat is in the closed state just before the suddenload increase, the extra delay in opening will prolong the period oftime in which the engine is unnecessarily overheated.

Another problem occurs during engine start-up or warm-up. During thisperiod of time, the coolant temperature rises more rapidly than theinternal engine temperature. Since the thermostat is actuated by coolanttemperature, it often opens before the internal engine temperature hasreached its optimum value, thereby causing coolant in the water jacketto prematurely cool the engine. Still other scenarios exist where theengine coolant temperature cannot be sufficiently regulated to cause thedesired internal engine temperature.

When the internal engine temperature is not maintained at an optimumvalue, the engine oil will also not be at the optimum temperature.Engine oil life is largely dependent upon wear conditions. Engine oillife is significantly shortened if an engine is run either too cold ortoo hot. As noted above, a cold running engine will have less completecombustion in the engine combustion chamber and will build up sludgemore rapidly than a hot running engine. The sludge contaminates the oil.A hot running engine will prematurely break down the oil. Thus, morefrequent oil changes are needed when the internal engine temperature isnot consistently maintained at its optimum value.

Prior art cooling systems also do not account for the fact that theoptimum oil temperature varies with ambient air temperature. As theambient air temperature declines, the internal engine components loseheat more rapidly to the environment and there is an increased coolingeffect on the internal engine components from induction air. To counterthese effects and thus maintain the internal engine components at theoptimum operating temperature, the engine oil should be hotter in coldambient air temperatures than in hot ambient air temperatures. Currentprior art cooling systems cannot account for this difference because thecooling system is responsive only to coolant temperature.

In sum, the prior art approach of employing coolant temperature tocontrol the internal engine temperature is crude and inaccurate.

Despite the large number of ideas proposed to improve the performance ofengine cooling systems, there is still a need for cooling systemcomponents and techniques which allow the system to more effectivelymatch its performance to the instantaneous needs of the engine, whilestill meeting the plurality of other functions noted above which aredemanded of the cooling system. There is especially a need for a systemand technique for controlling the state of one or more flow controlvalves in engine cooling systems in accordance with predetermined engineand ambient temperature conditions, including the actual internal enginetemperature. The present invention fills that need.

SUMMARY OF THE INVENTION

A temperature control system, in a liquid cooled internal combustionengine equipped with a radiator, controls the state of a flow controlvalve for controlling flow of a temperature control fluid through apassageway in the engine. Sensors detect the engine oil temperature andthe temperature of the temperature control fluid. An engine computerreceives signals from the sensors and compares the signals topredetermined values. In one embodiment, the engine computer comparesthe engine oil temperature signal to a predetermined value to controlactuation of the valve.

In another embodiment, the engine computer compares the engine oiltemperature signal to a predetermined engine oil temperature value. Theengine computer adjusts a predetermined temperature control fluidtemperature value based on the comparison of the engine oil temperaturesignal to the predetermined engine oil temperature value. The enginecomputer then compares the temperature control fluid temperature signalto the adjusted temperature control fluid temperature. The enginecomputer actuates the flow control valve based on the comparison of thetemperature control fluid temperature signal to the adjusted temperaturecontrol fluid temperature.

The foregoing and other objects features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of the preferred embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form which is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 is a top plan view of one preferred form of a hydraulicallyoperated electronic engine temperature control valve for controlling theflow of temperature control fluid in an engine.

FIG. 2 is a sectional side view of the valve in FIG. 1, taken along line2--2 in FIG. 1.

FIG. 3 is a different sectional side view of the valve in FIG. 1, takenalong line 3--3 in FIG. 1.

FIG. 4 is yet another sectional side view of the valve in FIG. 1, takenalong line 4--4 in FIG. 1.

FIG. 5 is a horizontal sectional view of the valve in FIGS. 1 and 2,taken along line 5--5 in FIG. 2.

FIG. 6 is a diagrammatic view of the valve in FIG. 1 connected to partsof an engine.

FIG. 7 is sectional side view of a preferred form of a multi-functionvalve which controls the flow of temperature control fluid to pluralparts of an engine, shown in a first position.

FIG. 8 is sectional side view of the multi-function valve of FIG. 7,shown in a second position.

FIG. 9 is a sectional side view of a piston type hydraulically operatedelectronic engine temperature control valve for controlling the flow oftemperature control fluid in an engine.

FIG. 10 is an end view of the valve in FIG. 9.

FIG. 11 is a sectional side view of another embodiment of a piston typehydraulically operated electronic engine temperature control valve forcontrolling the flow of temperature control fluid in an engine.

FIG. 12 is an end view of the valve in FIG. 11.

FIG. 13A is an enlarged view of a stationary rod seal employed in theembodiment of the invention shown in FIG. 7.

FIG. 13B is an enlarged view of a gasket seal employed in the embodimentof the invention shown in FIG. 7.

FIG. 14A is a diagrammatic illustration of one embodiment of thetemperature control system according to the present invention employingthe temperature control valve in a GM 3800 V6 transverse internalcombustion engine during normal operation.

FIG. 14B is a diagrammatic illustration of the temperature controlsystem of FIG. 14A during the warm-up phase.

FIG. 14C is a diagrammatic illustration of a second embodiment of thetemperature control system of the present invention employing the novelEETC valve to control flow to the radiator in a GM 3800 V6 transverseinternal combustion engine during the warm-up phase.

FIG. 14D is a diagrammatic illustration of the second embodiment of thetemperature control system of FIG. 14C during normal operation showingpart of the TCF flowing to the radiator and part flowing through theintake manifold and the oil pan.

FIG. 14E is a diagrammatic illustration of a third embodiment of thetemperature control system of the present invention employing a remoteshut-off valve (as shown in FIGS. 8 and 33) in a GM 3800 V6 transverseinternal combustion engine during normal operation.

FIG. 14F is a diagrammatic illustration of the third embodiment of thetemperature control system of FIG. 14E during normal operation showingthe TCF flowing to the radiator.

FIG. 15 is an exploded view of a portion of the valve in FIG. 2 showinga preferred embodiment of a diaphragm and how it attaches to the valvehousing.

FIGS. 16A and 16B are sectional views of a hydraulic fluid injectorsuitable for controlling the state or position of the valves in theinvention.

FIG. 16C is a sectional view of an alternative type of hydraulic fluidinjector suitable for controlling the state or position of the valves inthe invention.

FIG. 17 is a block diagram circuit of the connections to and from anengine computer for controlling the state or position of the valves inthe invention.

FIG. 18 is a diagrammatic sectional view of an engine block showing atemperature control fluid passageway through the engine block to an oilpan, for use with the valve shown in FIG. 7.

FIGS. 19 and 20 are graphs showing the state of a valve in the inventionat selected temperature control fluid and ambient air temperatures.

FIG. 21 is a graph showing the state of prior art wax pellet type orbimetallic coil type thermostats at the same selected temperaturecontrol fluid and ambient air temperatures of temperatures as in FIGS.19 and 20.

FIGS. 22A and 22B are graphs showing the state of a plurality of valvesin the invention at selected temperature control fluid and ambient airtemperatures.

FIG. 23 is a graph showing the actual temperature of the temperaturecontrol fluid when controlling the plurality of valves referred to inFIG. 22A according to the FIG. 22A scheme, compared to the actualtemperature of engine coolant when a prior art thermostat is employedand controlled according to the FIG. 21 scheme.

FIG. 24 is a graph showing the state of a valve in the invention atselected temperature control fluid and ambient air temperatures fornormal (low) engine load and high engine load conditions.

FIG. 25 shows a plot of the optimum engine oil temperature at selectedambient air temperatures.

FIG. 26 is a graph showing the state of a valve in the invention atselected temperature control fluid and ambient air temperatures fornormal (low) engine load conditions and during start-up/warm-up.

FIG. 27 is a flowchart showing a system for determining valve statesbased on multiple engine operating conditions shown in FIGS. 24 and 26.

FIG. 28 is a block diagram circuit of the connections to and from anengine computer for controlling the state or position of the valves inthe invention according to the multiple engine operating conditionsshown in FIGS. 24 and 26.

FIG. 29 is a graph of the actual engine oil temperature at selectedambient air temperatures when employing the invention in FIGS. 24-28.

FIG. 30 shows a trend line of temperature control fluid temperature andoil temperature during vehicle operation when employing the invention inFIGS. 24-28.

FIG. 31A is an idealized diagrammatic view of temperature control fluidflow paths through an engine including the intake manifold and the oilpan during warm-up.

FIG. 31B is an idealized diagrammatic view of temperature control fluidflow paths through an engine including the intake manifold and the oilpan during normal operation with the EETC valve partially open.

FIG. 32A is an idealized diagrammatic view of a second embodimentshowing the temperature control fluid flow paths through an engineincluding the intake manifold and the oil pan during warm-up.

FIG. 32B is an idealized diagrammatic view of the second embodiment ofFIG. 32A showing the temperature control fluid flow paths during normaloperation.

FIG. 33 is a diagrammatic sectional view of an engine block showingrestrictor/shutoff flow control valves in accordance with the invention.

FIG. 34 is a sectional side view of the restrictor/shutoff valve mountedto a fluid passageway.

FIG. 35 is an exploded view of the parts of the restrictor/shutoff valvein FIG. 34.

FIG. 36 is a sectional view of the restrictor/shutoff valve in FIG. 34,taken along line 36--36 in FIG. 34.

FIG. 37 is a sectional view of the restrictor/shutoff valve in FIG. 34,taken along line 37--37 in FIG. 34.

FIG. 38 is a sectional side view of an alternative embodiment of therestrictor/shutoff valve in its environment for simultaneouslycontrolling fluid flow in two different passageways.

FIG. 39 is a diagrammatic sectional view of the water jacket in anengine block showing how the restrictor/shutoff valve controls fluidflow in interior and exterior passageways of the water jacket.

FIG. 40 is a diagrammatic view of the coolant circulation flow paththrough a prior art engine when a thermostat is closed.

FIG. 41 is an idealized diagrammatic view of the coolant circulationflow path through a prior art engine when a thermostat is open.

FIG. 42 is an actual diagrammatic view of the coolant circulation flowpath through a prior art engine when a thermostat is open.

FIG. 43 is a sectional side view of a preferred form of a multi-functionvalve which controls the flow of temperature control fluid to pluralparts of an engine.

FIG. 44A is a diagrammatic illustration of an alternate embodiment ofthe temperature control system according to the present invention in aninternal combustion which includes a by-pass waterjacket for assistingin engine warm-up.

FIG. 44B is a diagrammatic illustration of the temperature controlsystem shown in FIG. 44A during normal operation.

FIG. 45A is a graphical illustration of one method for adjusting thetemperature control fluid temperature component.

FIG. 45B is a graphical illustration of the result of adjusting thetemperature control curve to account for engine conditions.

FIG. 45C is a graphical illustration of another method for adjusting thetemperature control fluid temperature component.

FIG. 46 is an empirical curve showing the actual engine oil temperatureand the temperature control fluid temperature over a time period duringwhich the engine was subjected to varying load conditions.

FIG. 47 is an actual plot of data generated on a GM 3800 V6 engine whileexperiencing varying load conditions.

FIG. 48 is a graphical illustration of an alternate embodiment of thepresent invention wherein a constant desired oil temperature isutilized.

FIG. 49 is an illustration of an electronically assisted thermostat foruse in a temperature control system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

While the invention will be described in connection with a preferredembodiment, it will be understood that it is not intended to limit theinvention to that embodiment. On the contrary, it is intended to coverall alternatives, modifications and equivalents as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

Certain terminology is used herein for convenience only and is not betaken as a limitation on the invention. Particularly, words such as"upper," "lower," "left," "right," "horizontal," "vertical," "upward,"and "downward" merely describe the configuration shown in the figures.Indeed, the valves and related components may be oriented in anydirection. For example while a vertically oriented radiator isillustrated in the figures, a horizontally oriented radiator is wellwithin the scope of the invention.

Apparatus depicting the preferred embodiments of the novel electronicengine temperature control valve are illustrated in the drawings.

FIG. 1 shows a top plan view of electronic engine temperature controlvalve 10 (hereafter, "EETC valve 10") as it would appear attached to anengine temperature control fluid passageway 12. (Only a portion of thepassageway 12 is visible in this view.) The EETC valve 10 is attached tothe passageway 12 by mounting bolts 14. The EETC valve 10 includes twomajor subcomponents, a valve mechanism 16 and a pair of solenoidactuated hydraulic fluid injectors 18 and 20. The injector 18 is a fluidinlet valve and the injector 20 is a fluid outlet valve. In effect, theinjectors 18, 20 are one-way flow through valves. The view in FIG. 1shows valve housing sub-parts including housing 22 of the valvemechanism 16 and housings 24 and 26 of the respective hydraulic fluidinjectors 18 and 20. The EETC valve 10 also includes fluid pressuresensor 28 mounted to the valve housing through insert 30. In thepreferred embodiment, the insert 30 is a brass fitting.

Also visible in FIG. 1 are electrical terminals 32, 34, and fluid inletand outlet tubes 36, 38, associated with respective fluid injectors 18and 20. These tubes are attached to respective solid tubes which feedinto the valve housing through inserts 30. Those inserts 30 are notvisible in this view. However, the insert 30 associated with the inlettube 36 is visible in FIG. 3. The inlet tube 36 is connected to a sourceof pressurized hydraulic fluid, such as engine lubrication oil. Theoutlet tube 38 is connected to a low pressure reservoir of the hydraulicfluid, such as an engine lubrication oil pan. Each of the electricalterminals 32, 34 are connected at one end to a solenoid inside of itsrespective fluid injector (not shown) and at the other end to acomputerized engine electronic control unit (ECU) (not shown).

FIG. 2 shows a sectional side view of one version of the EETC valve 10,taken along line 2--2 in FIG. 1. In this version, the EETC valve 10 is ahydraulically actuated diaphragm valve 40. The diaphragm valve 40reciprocates within the valve housing 22 along axis A between a firstand second state or position. The solid lines in FIG. 2 shows the valve40 in the first position which is associated with a valve "closed"state. FIG. 2 also shows the valve's second position in phantom which isassociated with a valve "open" state. In the first "closed" position,the valve 40 prevents flow of temperature control fluid (hereafter,"TCF") through passageway opening 42. In the second "open" position, thevalve 40 allows fluid flow through the opening 42. The opening 42 leadsto the engine radiator (not shown). Also visible in FIG. 2 is theelectrical terminal 34 and the outlet tube 38 associated with thesolenoid 20, the fluid pressure sensor 28, and one of the mounting bolts14.

The temperature control fluid (TCF) referred to herein is typicallyknown in the art as "coolant." Coolant is a substance, ordinarily fluid,used for cooling any part of a reactor in which heat is generated.However, as will be described below, the TCF not only removes heatenergy from engine components but is also employed in certainembodiments to deliver heat energy to certain engine components. Thus,the TCF is more than merely a coolant. Likewise, while the prior artreferenced herein relates to engine cooling systems, the inventionherein employs its unique valve(s) in an engine temperature controlsystem, providing both cooling and heating functions to enginecomponents.

Turning again to FIG. 2, the valve 40 reciprocates within the valvemechanism housing 22. The housing 22 is constructed of body 44 and cover46, held together by band clamp or crimp 48. The body 44 includes agenerally horizontal dividing wall 50 which divides the body 44 intoupper compartment 52 and lower compartment 54. (It should be recognizedthat the dividing wall 50 is a generally cylindrical disk in threedimensions.) The center of the dividing disk or wall 50 has a circularbore to allow passage of a reciprocating valve shaft or rodtherethrough, as described below. A cylindrical collar 56 extendsvertically upward and downward from the inner edge of the dividing wall50, thereby coinciding with the outer circumference of the circularbore. The collar 56 is integral with the dividing wall 50. The lower endof the lower compartment 54 leads to the opening 42.

As noted above, the valve 40 reciprocates between a first "closed"position wherein the valve 40 prevents flow of TCF through passagewayopening 42 and a second "open" position wherein the valve 40 allowsfluid flow through the opening 42. When the valve 40 is "closed," thewater pump circulates the TCF only through the engine block waterjacket. If the heater or defroster is in operation, the fluid is alsocirculated through a heat exchanger for the passenger compartmentheater, typically a heater core. When the valve 40 is "open," most ofthe TCF flows through the radiator before it is circulated through theengine block water jacket and the heater's heat exchanger.

Thus, in the embodiment of the invention shown in FIG. 2, the valve 40functions in a manner similar to the prior art wax pellet thermostat.However, unlike the fixed temperature wax pellet thermostat, the valve40 is electronically controlled and thus can be opened and closedaccording to a computer controlled signal tailored to specific engineoperating conditions and ambient environmental conditions.

The diaphragm valve 40 includes upper chamber 58, diaphragm 60, plate62, lower chamber 64, shaft or rod 66, valve member 68 and biasingspring 70. The diaphragm 60, plate 62 and spring 70 are disposed in thehousing body's upper compartment 52. The diaphragm 60 separates thehousing body's upper compartment 52 into the upper and lower chambers58, 64. The spring 70 is seated on one side against a lower surface ofthe plate 62 and on the other side against an upper surface of thehousing body's dividing wall 50. The rod 66 is also seated on one sideagainst the lower surface of the plate 62 and extends through thehousing body's upper and lower compartments 52, 54. The diaphragm 60 ismechanically linked to the valve member 68 through the plate 62 and therod 66. The position of the diaphragm 60 is thus communicated throughthe plate 62 and the rod 66 to the valve member 68, thereby causing thevalve member 68 to reciprocate between the first and second positions,shown in solid and in phantom, respectively.

The lower chamber portion of the body 44 includes air bleed opening 72therethrough for removing and reintroducing air into the lower chamber64 as the diaphragm valve 40 is moved between its first and secondpositions. Radial O-ring 74 prevents the hydraulic fluid from leakingout of passage 76.

The valve 40 also includes a gasket seal 78 around the periphery of theopening 42 to allow the valve member 68 to close off flow through theopening 42 when the valve 40 is in the first position. In the preferredembodiment of the invention, the gasket seal 78 also functions as thevalve seat for the valve member 68. The gasket seal 78 is generallysquare in vertical cross-section, although other shapes are contemplatedby the invention. One preferred type of gasket seal material is Viton®,manufactured by E.I. Du Pont De Nemours & Co., Wilmington, Del. AnO-ring 80 is disposed within the outer circumference of the rod 80 toprevent TCF in the lower compartment 54 from leaking into the valve'slower chamber 64.

In the preferred embodiment of the invention, the diaphragm 60 possessesspecial characteristics to allow it to more easily withstand very highpressures. Details of the diaphragm 60 are more fully discussed withrespect to FIG. 15.

The diaphragm valve upper chamber 58 is in fluid communication withhydraulic fluid passageway 82 through opening 84 therebetween. The fluidpassageway 82 is in fluid communication with the outlet of the hydraulicfluid injector 18 and the inlet of the hydraulic fluid injector 20through the passage 76, as best shown in FIG. 4. The fluid passageway isalso in fluid communication with the fluid pressure sensor 28 to allowthe pressure in the passageway to be monitored for controlling the valvestate. Diaphragm valves of the size suitable for installation in anengine fluid passageway can typically withstand pressures in the rangeof 200 psi. The diaphragm strength is typically the first component tofail due to excessive high pressure. Pressure monitoring helps to ensurethat pressures do not exceed those which the valve components can safelyhandle.

A warning system can be incorporated which would send a signal from thepressure sensor 28 to the ECU when the pressure exceeds or falls below apredetermined limit, such as if there is a loss of hydraulic pressure.The ECU could then display a suitable warning to the operator.Additionally, override mechanisms, such as an electro-mechanical device,could be activated to lock the EETC valve in the open position therebymaintaining flow to the radiator during valve failure.

In the preferred embodiment of the invention, the diaphragm includescertain features to allow it to better withstand a high pressureenvironment. FIG. 15 shows a preferred diaphragm and an exploded view ofthe preferred manner in which the diaphragm is mounted in the diaphragmvalve mechanism housing to achieve the best results under high pressure.

Unlike prior art diaphragm valves, such as disclosed in U.S. Pat. No.4,484,541, which are actuated and deactuated by applying and removing avacuum to and from an upper chamber, the diaphragm valve 40 disclosedherein is actuated by pressurized and depressurizing the upper chamber58 with hydraulic fluid. A hydraulic fluid system has numerousadvantages over a vacuum actuated system including less sensitivity totemperature extremes, and increased accuracy, durability andreliability. These are very considerations since the EETC system mustfunction under a multitude of extreme conditions, both environmental andphysical. Accordingly, a reliable power source is required and one ofthe most dependable sources of hydraulic fluid in an engine ispressurized engine oil.

The EETC internal engine circuit is generally operating at highertemperatures to optimize engine performance. These higher temperaturesrequire higher pressures to actuate the EETC valve (e.g., about 10pounds of force). Standard electro-mechanical solenoid-type orvacuum-type valves may experience operational problems during the worstcase conditions. The novel EETC valve of the present invention isdesigned to provide the force required to actuate the valve when lessthan 50% of normal engine oil pressure is available, such as when thereis a low amount of oil present, a high oil temperature, or the oil pumpis worn. Accordingly, the hydraulically actuated EETC valve disclosed isthe preferred valve for the disclosed system.

In operation, the valve 40 functions as follows. When the engine isoperating and it is desired to open the valve 40, the ECU sends acontrol signal to the solenoid of the hydraulic fluid injector 18 toopen the injector's valve. Simultaneously, the ECU sends a controlsignal to the solenoid of the hydraulic fluid injector 20 to close thatinjector's valve, if it is not already closed. Pressurized hydraulicfluid from the fluid inlet tube 36 flows through the fluid injector 18,the hydraulic fluid passageway 82, the opening 84 and into the valveupper chamber 58, where it pushes against the diaphragm 60 and plate 62.When the fluid pressure against the diaphragm 60 and plate 62 exceedsthe opposing force of the biasing spring 70, the diaphragm 60 movesdownward, thereby causing the valve member 68 to move downward. Theupper chamber 58 expands as the diaphragm 60 and plate 62 movesdownward. As the upper chamber 58 fills with fluid, the pressure in thechamber rises. When the pressure sensor 28 detects that the fluidpressure has reached a predetermined level, it causes the ECU to start atimer which runs for a predetermined period of time. After that time hasexpired, the ECU sends a control signal to the solenoid of the hydraulicfluid injector 18 to close the injector's valve. The hydraulic fluid inthe upper chamber 58 thus remains trapped therein.

The predetermined pressure level and time period are empiricallydetermined so as to allow the valve member 68 to reach its open orsecond position. To avoid excessively activating the injector'ssolenoids, the open injector valve should be closed as soon as thediaphragm valve 40 has reached the desired state. Also, a diaphragmvalve 40 is selected which will always open under less pressure thanexists in the hydraulic fluid system that the inlet fluid injector 18 isattached to. To remove air trapped in the upper chamber 58 and/orconnected passageways, the ECU can be programmed to open the valve ofthe outlet fluid injector 20 for a short period of time (e.g., onesecond). This is similar to the technique for bleeding air from avehicle's hydraulic braking system.

If hydraulic fluid leaks out of the upper chamber 58, the pressuresensor 28 will immediately sense this condition. The ECU responds byagain sending a control signal to the solenoid of the hydraulic fluidinjector 18 to open the injector's valve. When the pressure sensor 28detects that the fluid pressure has again reached the predeterminedlevel, it causes the ECU to start a timer which runs again for apredetermined period of time. After that time has expired, the ECU sendsa control signal to the solenoid of the hydraulic fluid injector 18 toclose the injector's valve.

The process of opening the EETC valve is automatically delayed by theECU during engine start-up until the source of the hydraulic fluidpressure reaches it normal operating level. In one embodiment of theinvention which employs engine lubrication oil as the hydraulic fluid,the delay period is about two or three seconds to allow for lubricationof all critical engine components.

When it is desired to close the valve 40, the above steps are reversed.That is, the ECU sends a control signal to the solenoid of the hydraulicfluid injector 18 to close the injector's valve, if it is not alreadyclosed. Simultaneously, the ECU sends a control signal to the solenoidof the hydraulic fluid injector 20 to open that injector's valve. Thepressurized hydraulic fluid inside the upper chamber 58 flows out of theupper chamber 58 through the opening 84, into the hydraulic fluidpassageway 82, through the open valve of the hydraulic fluid injector 20and into the fluid outlet tube 38. The fluid outlet tube 38 connects toa reservoir (not shown) of hydraulic fluid. As the hydraulic fluidempties out of the upper chamber 58, biasing spring 70 pushes thediaphragm 60 and plate 62 upward, thereby causing the valve member 68 tomove upward until the valve 40 becomes closed. When the pressure sensor28 detects that the upper chamber 58 is no longer pressurized, it causesthe ECU to send a control signal to the solenoid of the hydraulic fluidinjector 20 to close that injector's valve.

The vehicle's engine does not need to be operating to close the valve40. Thus, during a "hot engine off soak" (i.e., the time periodsubsequent to shutting off a hot engine), the valve 40 stays open sincethe hydraulic fluid remains trapped in the upper chamber 58. Thisfunction mimics prior art cooling systems which maintain an open path tothe radiator until the thermostat's wax pellet rehardens. After theengine has cooled down, the ECU (which is powered from the vehicle'sbattery) causes the valve 40 to close, as described above.

FIG. 3 shows a different sectional side view of the diaphragm version ofthe EETC valve 10, taken along line 3--3 in FIG. 1. This view moreclearly shows the entire path of the TCF from a passageway leading fromthe engine block water jacket, through the valve 40 and to the radiator.As noted above, if the valve 40 is closed, the TCF circulates directlyback into the engine block water jacket, without being diverted into theradiator.

FIG. 3 also shows the inlet hydraulic fluid injector 18 and the fluidinlet tube 36 leading thereto, along with the insert 30 associatedtherewith. As noted above, the insert 30 is preferably a brass fitting.The passageway 82 from the outlet of the injector's valve to the upperchamber 58 is not visible in this view but is clearly shown in FIG. 4.The fluid connection or path between the fluid inlet tube 36 and theinjector 18 is also not visible in this view but is understandable withrespect to FIG. 6.

FIG. 4 shows yet another sectional side view of the diaphragm version ofthe EETC valve 10, taken along line 3--3 in FIG. 1. This view showsfluid passageway 86 from the outlet of the hydraulic fluid injector 18to the passage 76 leading to the diaphragm upper chamber 58, and fromthe upper chamber 58 to the passage 76 leading from the hydraulic fluidinjector 20. Again, the fluid connections or paths between the fluidinlet and outlet tubes 36, 38 and the respective injectors 18, 20 arealso not visible in this view but are understandable with respect toFIG. 6.

FIG. 5 is a horizontal sectional view of the EETC valve 10 in FIGS. 1and 2, taken along line 5--5 in FIG. 2. This view shows more of theinternal structure of the valve parts.

FIG. 6 shows diagrammatically the preferred embodiment of how the EETCvalve 10 connects to a source of hydraulic fluid. In this embodiment ofthe invention, the source of hydraulic fluid is engine lubrication oil.In FIG. 6, a portion of oil pan 94 is cut away to show enginelubrication oil pump 90 and engine lubrication oil reservoir 92 in oilpan 94. As is well known in the art, outlet 96 of the oil pump 90 feedsoil to practically all of the engine moving parts under pump pressurethrough distributing headers (not shown). To provide a source ofpressurized hydraulic fluid to the inlet fluid injector 18, the fluidinlet tube 36 is connected to the oil pump outlet 96. An optionalreplaceable filter 98 may be placed in the pressurized oil line toensure that the oil flowing to the valve 10 does not clog the injectors.To provide a return path for the hydraulic fluid exiting from the outletfluid injector 20, the fluid outlet tube 38 is connected to the oilreservoir 92 in the oil pan 94.

FIGS. 7 and 8 show another preferred form of an EETC valve 100 whichsimultaneously controls the flow of TCF to plural parts of an engine. Ina first embodiment, the EETC valve 100 controls fluid flow to theradiator and the oil pan. When the EETC valve 100 is in a firstposition, flow to the radiator is blocked and flow to the oil pan ispermitted. When the EETC valve 100 is in a second position, flow to theradiator is permitted and flow to the oil pan is blocked. FIG. 7 showsthe EETC valve 100 in the first position, whereas FIG. 8 shows the valvein the second position.

In a second embodiment, the EETC valve 100 controls fluid flow to theradiator, oil pan and a portion of the engine block water jacket. Inthis embodiment, that portion of the water jacket comprises the portionaround, for example, the intake manifold. When the EETC valve 100 is ina first position, flow to the radiator is blocked and flow to the oilpan and the intake manifold is permitted. When the EETC valve 100 is ina second position, flow to the radiator is permitted, flow to the oilpan is blocked, and flow to the intake manifold is either restricted orblocked. Again, FIG. 7 shows the EETC valve 100 in the first position,whereas FIG. 8 shows the valve in the second position. Alternately, theEETC valve can control fluid flow to the cylinder head, or water pumpinstead of, or in conjunction with, the intake manifold of the secondembodiment.

The EETC valve 100 employs a diaphragm valve 102. The sectional view inFIG. 7 is slightly different than the section taken of EETC valve 10through line 2--2 in FIG. 1 so as to show the TCF passage through theEETC valve 100. It should be noted that a top plan view of the EETCvalve 100 will appear identical to EETC valve 10 shown in FIG. 1.Furthermore, the valve parts and housing of EETC valve 100 differ onlyslightly from the EETC valve 10. One difference between EETC valve 10and EETC valve 100 lies in the shape of the housing body's dividing walland collar attached thereto. In the embodiment of the invention shown inFIG. 7, dividing wall 104 has a unique shape to allow it to accept aunique stationary rod seal 106. The seal 106 performs a function similarto the O-ring 80 shown in FIG. 2. That is, the seal 106 prevents TCF inthe valve's lower compartment 108 from leaking into the valve's lowerchamber 142. The EETC valve 100 is similar to the EETC valve 10 in thatits housing 112 includes a body 114 and a cover 116, held together byband clamp or crimp 118.

The dividing wall 104 in FIG. 7 is, preferably, defined by threeintegrally formed portions, a downwardly tapered portion 120 attached atone end to a sidewall of housing 112, a generally vertical portion 122attached at one end to the other end of the tapered portion 120, and agenerally horizontal portion 124 attached at one end to the other end ofthe generally vertical portion 122. The center of the dividing wall 104has a circular bore to allow passage of reciprocating valve rod 126therethrough, in the same manner as the valve rod in EETC valve 10.Thus, the generally horizontal portion 124 does not extend completelyacross the radius of the housing 112. A cylindrical collar 128 extendsvertically upward from the other end of the horizontal portion 124(i.e., from the inner edge of the dividing wall 104), thereby coincidingwith the outer circumference of the circular bore. Unlike the collar 56in diaphragm valve 40, the collar 128 does not extend downward from thedividing wall 104. Instead, the dividing wall 104 includes an integrallyformed extension flange 130 which extends perpendicularly downward by ashort distance from a center region of the horizontal portion 124. Theunique stationary rod seal 106 is attached to a lower surface of thedividing wall 104 as best shown in FIG. 13A.

FIG. 13A shows an enlarged view of the circled dashed region in FIG. 7associated with the stationary rod seal 106. Reciprocating valve rod 126moves along axis A adjacent to the inner sidewall of the dividing wall'shorizontal portion 124. The extension flange 130 includes a curved outerwall surface 132 and a generally planar inner wall surface 134. Theextension flange 130 extends downward from the horizontal portion by adistance of about d₁. A cylindrical seal 136 having a generallyrectangular vertical cross-section is fit into the space between theextension flange's inner wall surface 134 and the outer circumferentialwall of the rod 126 (or the outer circumferential wall of the dividingwall's bore, if the rod 126 is not yet inserted into place). The seal136 has a vertical width slightly less than d₁ so that the seal 136 liesapproximately flush with a horizontal plane formed by the lower surfaceof the extension flange 130. The seal 136 also has a circular impressiontherein for accepting O-ring 138. Retention cup 140 is attached to thelower surface of the extension flange 130 and the seal 136. The outeredge of the cup 140 wraps around the curved outer wall surface 132 ofthe extension flange 130.

One suitable material for the retention cup 140 is a brass cup crimpedover the curved outer wall surface 132. A suitable material for the seal136 is a standard Vitron® material type POLYPAK® retention sealmanufactured by Parker-Hannifin Corp., Cleveland, Ohio. A suitable rod126 will have an outer diameter of about 3/8 inch. A stationary rod seal106 constructed with those materials will withstand TCF pressures of atleast 50 psi.

The stationary rod seal 106 inhibits debris which becomes lodged on thelower portion of the rod 126 from traveling up into the valve's lowerchamber 142 when the rod 126 moves from the second position shown inFIG. 8 to the first position shown in FIG. 7. The stationary rod seal106 effectively acts as a wiper, dislodging any such debris from the rod126 and depositing in the valve's lower compartment 108 where it can becarried away by the TCF.

The dividing wall 104/stationary rod seal 106 feature in EETC valve 100can replace the dividing wall/O-ring sealing structure in EETC valve 10.

Turning again to FIG. 7, the diaphragm valve 102 includes a reinforcedgasket seal 144. The details of the gasket seal 144 are shown moreclearly in FIG. 13B. The gasket seal 144 also functions as the valveseat for valve member 146.

FIG. 13B shows an enlarged view of the circled dashed region in FIG. 7associated with the gasket seal 144. The gasket seal 144 provides twofunctions. First, it functions as a sealing seat for the valve member146. Second, it prevents the TCF from flowing into the valve's lowercompartment 108 when the EETC valve 100 is in the first position.

The gasket seal 144 includes an elastomer material 148 having a cut-out150. A washer 152, preferably of stainless steel, is snapped into thecut-out 150. The washer 152 limits the travel of the valve member 146 bystrengthening and supporting the gasket seal 144, thereby increasing theintegrity of the seal 144. If the cut-out 150 and washer 152 were notpresent, the valve member 146 would be more prone to push through theelastomer material 148 under high pressure conditions. To inhibit thisfrom occurring, the inner diameter of the washer 152 is dimensioned tobe smaller than the outer diameter of the bottom of the valve member146. In an alternate embodiment, the gasket seal 144 is made entirely ofmetal material and functions to limit the travel of the valve member146. Other seal configurations are also contemplated by the presentinvention.

The gasket seal 144 is pressed into a cut-out 154 in a wall of TCFpassageway 156, although it may also be located in a cut-out of a wallof the valve's lower compartment 108. The cut-out 154 and the washer'scut-out 150 are dimensioned so that an outer diameter portion of thewasher 152 recesses in the wall. This arrangement tightly traps thewasher 152 into position.

As noted above, the first embodiment of the EETC valve 100 controlsfluid flow to the radiator and the oil pan. This is accomplished byincluding an opening 158 in the TCF passageway 156 leading to anadditional TCF passageway 160. The passageway opening 158 is positionedwithin the passageway 156 so that when the valve member 146 is in thefirst position (as shown in FIG. 7), the valve member 146 does not blockthe opening 158, thereby allowing flow of a portion of the fluidtherethrough. When the valve member 146 is in the second position (asshown in FIG. 8), the valve member 146 becomes seated against theopening 158, thereby closing the opening 158, and thus preventing flowof any of the fluid therethrough.

The diaphragm valve 102 does not need to be modified to provide theadditional control function associated with the fluid flow to the oilpan. It is only necessary to position the opening 158 so that the valvemember 146 seats over it at the end of its stroke, as shown in FIG. 8.

FIG. 15 shows the preferred diaphragm 102 exploded from the housing body114 and valve cover 116. The diaphragm 102 is formed from a flexiblematerial which moves between the first position shown in FIG. 7 and thesecond position shown in FIG. 8 as hydraulic fluid fills into andempties from the diaphragm valve's upper chamber. The diaphragm 102includes an integrally molded O-ring type flange 110 which extendsdownward from the outer circumference and seats into groove 162 formedin the upper edge of the body 114. The diaphragm also includes anintegrally molded bead 164 on the top side of the flange 110. Thepreferred material for the diaphragm 102 is an elastomer 166, coveredwith fabric 168 on its lower surface. One suitable combination ofelastomer and fabric is Viton® and Nomex®, both manufactured by E.I. DuPont De Nemours & Co., Wilmington, Del. This type of diaphragm isdesigned by RPP Corporation, Lawrence, Mass.

The size of the diaphragm 102 is determined by the dimensions of theEETC valve 100. In one embodiment of the invention wherein the EETCvalve 100 is sized to replace a prior art wax pellet or bimetallic coiltype thermostat, a suitable diaphragm 102 will have the followingdimensions:

1. end-to-end diameter of about 1.87 inches;

2. top-to-bottom height of about 0.55 inches;

2. flange diameter and height of about 0.094 inches; and

3. bead 164 radius of about 0.015 inches.

A diaphragm 102 sized as such will fit into a cylinder bore having adiameter of about 1.43 inches and will accept an upper plate of a pistonrod having a diameter of about 1.18 inches.

Since FIG. 15 shows the preferred embodiment of the housingbody/diaphragm/valve cover subassembly, it should be understood that theequivalent subassembly in the EETC valve 10 also preferably employs thisembodiment. The diaphragm in the EETC valve 10 has an integrally moldedO-ring type flange which extends upward from the outer circumference andseats into a groove formed in the lower edge of the valve cover. Thediaphragm in the EETC valve 10 is also preferably an elastomer, coveredwith fabric on its lower surface. The diaphragm in the EETC valve 10does not include an integrally molded bead on an opposite side of theflange. Accordingly, it is easier and cheaper to manufacture.

The particular features of the diaphragm 102 and the manner in which itis assembled between the housing body 114 and valve cover 116 allows thediaphragm 102 to withstand larger pressures than the diaphragm of theEETC valve 10.

FIG. 14A diagrammatically shows one embodiment of the temperaturecontrol system according to the present invention in a GM 3800 V6transverse internal combustion engine. The system includes a modifiedversion of the multi-function EETC valve 100 of FIGS. 7 and 8, withfluid paths to the intake manifold and the oil pan. The fluid flow pathsto and from the automobile heater are not shown in this simplifieddiagram. The system shown in FIG. 14A functions as follows.

When the diaphragm valve 102 is in the second position similar to thatshown in FIG. 8 (i.e., open to TCF flowing to the radiator, closed toTCF flowing to the intake manifold/oil pan), the TCF enters a TCF jacket200 formed in a cylinder block. From there, it is supplied to throughpassageways 202' to the cylinder head waterjacket 202. The TCF leavingthe jackets 200 and 202 flows through the valve 102 of EETC valve 100and is introduced to radiator 206 through radiator inlet passage 208.The TCF which enters the radiator 206 is cooled during its passagetherethrough by air flow from cooling fan 210 located at the rear sideof the radiator 206. The cooled TCF is supplied to a TCF pump 212 (e.g.,a water pump) through the radiator outlet passage 214. The TCF suppliedto the pump 212 is again circulated to the jackets 200 and 202.

FIG. 14B illustrates the temperature control system when the diaphragmvalve 102 is in the first position, similar to that shown in FIG. 7(i.e., closed to TCF flowing to the radiator, open to TCF flowing to theintake manifold/oil pan). In this embodiment, the restrictors 400function to restrict and/or prevent the flow of the TCF from the engineblock jacket 200 to the cylinder head 202. Therefore, only a smallamount of the TCF entering jacket 200 is supplied to the cylinder headjacket 202 (indicated in the figures by the small arrows). The smallermass of TCF in the cylinder head will, accordingly, heat up quickly.Meanwhile the restricted mass of TCF in the block waterjacket 200operates as an insulator to prevent heat loss. The TCF leaving thecylinder head jacket 202 is prevented from entering the radiator inletpassage 208 by EETC valve 100. Hence, the TCF bypasses the radiator 206and enters the intake manifold jacket 204. From the intake manifoldjacket 204, the TCF flows to the oil pan 94 through bypass passageway216 and into heat exchanger 218. The heat exchanger 218 preferablycomprises a U-shaped heat conductive tube 220 which allows heat from theTCF to pass into the oil in the oil pan 94. Other tubing shapes are alsosuitable. The TCF exiting the heat exchanger 218 flows back into thepump 212 for recirculation into the engine block.

In cold temperature environments, or when an engine is first warmed up,the engine lubrication oil should be heated to its normal operatingtemperature as rapidly as possible, and maintained at that temperature.In prior art engine cooling systems, engine coolant is not employed toassist in this goal. To the contrary, prior art systems work againstthis goal by immediately circulating coolant through the jacket andremoving heat from the engine block, and, thus, from the engine oil,inhibiting it from reaching its optimum temperature as quickly aspossible.

The present invention helps to achieve that goal by circulating aportion of the TCF through the oil pan 94. Since the diaphragm valve 102is likely to be in the first position shown in FIG. 7 when the engine isin cold temperature environments, or when it is first warmed up, the oilin the oil pan 94 will receive warm or hot TCF when it needs it themost. The heat energy transferred from the warm or hot TCF into the oilallows the oil to more quickly reach its ideal operating temperature. Ineffect, the TCF diverted to the oil pan 94 recaptures some of theparasitic engine heat loss caused by circulation of the TCF.

The inventive system described herein allows the engine oil to capturesome of the heat energy in the TCF after the engine is turned off. Incontrast, the heat energy in the coolant of prior art cooling systems iswasted by being passed into the environment. Since the valve 102, in thepresent invention, will always be in the first position after enginecooldown, heat energy can pass by convection through the passageway 216and into the oil pan 94. If the ambient air temperature is very cold,the valve 102 may even remain in the first position during and afterengine operation. Thus, convective heating of the engine oil willcontinue after the engine is turned off. The mass of hot TCF has thepotential to keep the engine oil warm longer after engine shut-off. As aresult, the present invention provides substantial benefits insituations where an engine is subject to frequent on/off cycles, e.g.,delivery vehicles.

As noted above, the EETC valve 100 may operate in alternate embodiments.For example, a second embodiment incorporates the EETC valve 100 tophysically control fluid flow through the radiator. As a consequence ofinhibiting and permitting the flow to the radiator, the flow through theintake manifold and oil pan is controlled. This is diagrammaticallyshown in FIGS. 14C and 14D and operates as follows. When the EETC valve100 is in a first position, flow to the radiator is blocked and flowthrough the oil pan and through the intake manifold is permitted (e.g.,engine warm-up phase). When the EETC valve 100 is in a second position(FIG. 14D), flow to the radiator is permitted. The flow to intakemanifold and oil pan is not physically restricted, but the pressure fromthe water pump will cause a significant amount of the TCF to flowthrough the radiator with a minimal amount flowing through the intakemanifold and the oil pan.

A third embodiment of the temperature control system is shown in FIGS.14E and 14F. Operation of this embodiment of the EETC valve 100 is bestunderstood in conjunction with FIG. 8. The valve's hydraulic fluidpassageway 170 includes opening 172 leading to fluid outlet tube 174through housing insert 176, preferably a brass fitting. The outlet tube174 is, preferably, connected to an remotely located intake manifoldflow control valve. This valve is not shown in FIG. 8, but is labelledin FIG. 14E as valve 300. The valve 300 controls the flow of fluidthrough the intake manifold jacket 204 which surrounds the intakemanifold (not shown). For the purposes herein, the valve 300 can be anyvalve which is moved from a first position to a second position byhydraulic fluid pressure applied to a valve chamber, wherein the firstposition is associated with unrestricted fluid flow through anassociated passageway and the second position is associated with eitherrestricted or blocked flow through the passageway. One example of avalve 300 suitable for this purpose is described in FIGS. 33-39 of thisdisclosure. However, the valve 300 can comprise any type ofhydraulically fluid actuated valve such as a piston valve, diaphragmvalve or the like. Furthermore, while the preferred valve is actuated byhydraulic pressure, other actuation mechanisms are well within the scopeof this invention. The valve is shown positioned in close proximity tothe EETC valve 100 for the sake of convenience. It should be wellunderstood that the valve 300 may be placed at any suitable location forrestricting and/or blocking flow into the intake manifold jacket 204.

When it is desired to move the diaphragm valve 102 into the secondposition shown in FIG. 8, pressurized hydraulic fluid flows through thepassageway 170 into upper chamber 178. Simultaneously, a portion of thehydraulic fluid flows through the opening 172, into the fluid outlettube 174 and into the chamber (not shown) of the intake manifold flowcontrol valve 300. The pressurized fluid in this chamber causes thevalve 300 to move from the first position (unrestricted flow) to thesecond position (restricted or blocked flow).

When it is desired to move the diaphragm valve 102 back into the firstposition shown in FIG. 7, the hydraulic fluid in the upper chamber 178flows out through an outlet hydraulic fluid injector in the same manneras described with respect to FIGS. 2-5. Likewise, the hydraulic fluid inthe chamber of the valve 300 flows back into the EETC valve 100 and outthrough the outlet hydraulic fluid injector. In this manner, the stateof the EETC valve 100 determines the state of the valve 300.

The purpose of this control scheme is to reduce the amount of heatenergy flowing through the intake manifold when the engine is hot. In atypical internal combustion engine, the intake manifold has an idealtemperature of about 120 degrees Fahrenheit. In such engines, there isno significant advantage in heating the intake manifold to temperatureshigher than about 130 degrees Fahrenheit. In fact, extremely hot intakemanifold temperatures reduce combustion efficiency. This is due to thefact that air expands as it is heated. Consequently, as the air volumeexpands, the number of oxygen molecules per unit volume decreases. Sincecombustion requires oxygen, reducing the amount of oxygen molecules in agiven volume decreases combustion efficiency. Prior art cooling jacketstypically deliver coolant through the intake manifold at all times. Whenan engine is running hot, the coolant temperature is typically in arange from about 220 to about 260 degrees Fahrenheit. Thus, the coolantmay be significantly hotter than the ideal temperature of the intakemanifold. Nevertheless, the prior art cooling system will continue todeliver hot coolant through the intake manifold, thereby maintaining theintake manifold temperature in an excessively high range.

The second embodiment of the invention described herein employs the EETCvalve 100 to restrict or block the flow of TCF through the intakemanifold, thereby avoiding the unwanted condition described above. Whenthe EETC valve 100 is in the first position shown in FIG. 7, it islikely that the temperature of the TCF is below that which would causethe intake manifold to exceed its ideal operating temperature. Thus,when the EETC valve 100 is in the first position, flow of TCF throughthe intake manifold is permitted. The intake manifold flow control valvescheme can also be employed with the EETC valve 10 shown in FIGS. 2-5.This scheme functions with or without the modification to thetemperature control fluid passageway for diverting the fluid to the oilpan.

The valve 300 may, instead, be mounted at the end of the intake manifoldjacket 204 (not shown in the figures), thereby "dead heading" the flowof fluid through the jacket 204. "Dead heading" is used herein todescribe the state whereby the flow of fluid is blocked but the fluidstill remains in the water jacket passage due to the continuous pumpingof fluid by the engine's water pump. "Restricting" is used herein todescribe the state whereby the flow of fluid is partially blocked but aportion of the fluid still flows in the water jacket passage due to thecontinuous pumping of fluid by the engine's water pump. Since heatenergy is primarily transferred to and from the engine block by the flowof fluid, dead heading the flow will have almost the same effect asshutting off the flow. This is due, in part, to the cooling effectprovided by the air passing through the intake manifold, which operatesto extract the heat from the "stagnant" TCF in the water jacket of theintake manifold. A minimum amount of convective fluid heat flow willstill occur between the intake manifold jacket 204 and the cylinder headand block jackets 200 and 202 in this configuration, since the channelsbetween the cylinder head and the intake manifold are still open.However, it is more preferable to place the valve 300 in the passagewayleading to the beginning of the intake manifold jacket 204 (shown inFIGS. 14E and 14F), thereby preventing both fluid flow through theintake manifold jacket 204 and convective fluid heat flow between thejacket 204 and the jackets 200 and 202.

The configuration in FIGS. 14A through 14F wherein the EETC valve 100controls fluid flow to the radiator, oil pan and a portion of the engineblock water jacket (e.g., the portion around the intake manifold)produces a highly effective engine temperature control system in a widerange of ambient temperature condition, as well as during engine warmup. In cold temperature environments and during warm up, the EETC valve100 allows flow of the TCF to the oil pan and the intake manifold,thereby causing the engine oil and intake manifold to more rapidly reachtheir ideal operating temperatures. Once the engine is sufficientlywarmed up, or when the engine is operating in very hot ambient airtemperatures, the EETC valve 100 shuts off flow of the TCF to both theoil pan and the intake manifold since neither the oil, nor the intakemanifold need additional heat energy under either of those conditions.

The EETC valve 100 can also control the flow of the TCF to portions ofthe engine block water jacket other than the portion around the intakemanifold. The valve 300 shown in FIGS. 14E and 14F can, alternatively,be placed to block or restrict flow through portions of the cylinderblock jacket 200 or the cylinder head jacket 202. In another embodiment,a plurality of water jacket blocking/restricting valves can besimultaneously controlled from the hydraulic fluid system of thediaphragm valve 102. FIGS. 14A through 14F show such additional valves400 in phantom. FIG. 14F illustrates the restricting/shutting off ofsome of the channels 202' between the engine block 200 and the cylinderhead jacket 202.

The alternate embodiments shown in FIGS. 14A through 14F illustrate theuse of restrictor/shut-off valves to prevent or reduce the passage offluid to a portion of the cylinder head and/or the intake manifold. Asstated above, these configurations are beneficial when the engine iscold, such as during start-up, since they heat the oil to its optimumoperating temperature as soon as possible. Although constant circulationof the TCF fluid through the engine, without including the radiator,will eventually heat up the engine oil, doing so will take considerablylonger than desired. Accordingly, in these embodiments, the heat fromthe cylinder head and/or the intake manifold is channeled to the engineoil to heat it up directly. The EETC valve in these embodiments would,preferably, be similar to the valve depicted in FIG. 43. However, theflow would be directed to the intake manifold before proceeding to theoil pan.

The passageways controlled and the locations of the EETC andrestrictor/shut-off valves will, of course, vary depending on theconfiguration of the engine chosen. Those skilled in the art, uponreading this disclosure, will be readily capable of varying thedisclosed preferred embodiments without departing from the scope of theinvention.

The EETC valve 100 can also be employed to address a design compromiseinherent in prior art engine cooling systems employing prior artthermostats. Prior art FIGS. 40 and 41 show a simplified diagrammaticalrepresentation of coolant circulation flow paths through such an engine.The coolant temperature is represented by stippling densities, hotcoolant having the greatest density and cold coolant having the smallestdensity. FIG. 40 shows that when thermostat 1200 is closed, the coolantthat exits water jacket 1202 flows through orifice 1204, into the intakeside of water pump 1206, and then back to the water jacket 1202. Thus,the coolant circulates entirely within the engine water jacket 1202,avoiding radiator 1208. FIG. 41 shows that when the thermostat 1200 isopen, all of the coolant circulates through the radiator 1208, into theintake side of the water pump 1206, and then back to the water jacket1202.

FIG. 41 is an idealized diagram of coolant flow. Since fluid takes thepath of least resistance, most of the coolant will flow through thelarger opening associated with the thermostat 1200, as opposed to themore restrictive orifice 1204. However, a small amount of coolant stillpasses through the orifice 1204 and into the intake side of the waterpump 1206, as shown in prior art FIG. 42. Since this small amount ofcoolant is not cooled by the radiator 1208, it raises the overalltemperature of the coolant reentering the water jacket to a level higherthan is desired.

To minimize this problem, the opening associated with the thermostat1200 is made as large as possible and the orifice 1204 is made as smallas possible. However, if the orifice 1204 is made too small, circulationthrough the water jacket 1202 will be severely restricted when thethermostat 1200 is closed. This may potentially cause prematureoverheating of portions of the engine block and will reduce the amountof heat energy available for the heater and intake manifold duringengine start-up and in cold temperature environments. If the orifice1204 is made too large, the percentage of coolant flowing therethroughwill be large when the thermostat 1200 is open. Accordingly, the averagetemperature of the coolant returning to the water jacket 1202 will betoo hot to properly cool the engine.

Thus, prior art engine cooling systems must always attempt to strike theproper balance between extremes when sizing the orifice 1204, therebyresulting in a compromised, but never idealized, size. In an idealizedsystem, the orifice 1204 is open and large when the thermostat 1100 isclosed, and is closed when the thermostat 1200 is open.

FIG. 43 shows how the EETC valve 100 can be employed to create thisidealized system. FIG. 43 is similar to FIGS. 7 and 8, except that theopening 158 shown in FIGS. 7 and 8 is an orifice 1210 and this orifice1210 is the only fluid flow path for the TCF when the EETC valve 100 isin the first position shown in FIG. 7. That is, there is no alternativepath to the water pump when the EETC valve 100 is in the first positionwhich corresponds to the embodiments illustrated FIGS. 14A through 14F.This is in contrast to the system in FIG. 7 wherein a portion of the TCFflows through the opening 158 and into the passageway 160, and theremaining portion of the TCF flows to the water pump.

Since the orifice 1204 shown in FIGS. 40-42 merely functions as a pathfor coolant to return to the water pump 1206 for recirculation throughthe water jacket 1202, the system in FIG. 43 takes advantage of thisalready existing return path (shown in FIG. 18) to achieve the samefunction.

The orifice 1210 can be sized as large as allowed by the valve member146, and thus need not be restricted in size by the constraintsdescribed above with respect to the prior art engine cooling systems.The TCF flowing through the orifice 1210 travels through the passageway160 and follows the same path as shown in FIG. 18. When the EETC valve100 in the configuration shown in FIG. 43 is in the second position (notshown, but similar to FIG. 8), no TCF can flow through the orifice 1210,thereby achieving the idealized "no flow" state unattainable in theprior art system described above.

The EETC valve 100 can also be employed in an anticipatory mode toaddress one problem in prior art engine cooling systems, specifically,the problem of sudden engine block temperature peaks caused when aturbocharger or supercharger is activated. These sudden peaks, in turn,may cause a rapid rise in coolant temperature and engine oil temperatureto levels which exceed the ideal range. Since prior art cooling systemstypically cannot shut off flow of coolant to the intake manifold, therise in engine block temperature causes even more unnecessary heatenergy to flow around the already overheated intake manifold.Furthermore, if the engine is still warming up, the prior art wax pellettype thermostat might not even be open. The thermostat might also beclosed even if the coolant temperature has reached the range in which itshould open, due to hysteresis associated with melting of the wax.

The invention herein can employ the EETC valve 100 to lessen thetemperature rise effects of the turbocharger or supercharger. When theturbocharger or supercharger is activated, a signal can be immediatelydelivered to the EETC valve 100 to cause it to move into its secondposition, as shown in FIG. 8, if it is already not in that position.This will stop the flow of TCF to the engine oil and through the intakemanifold, in anticipation of a rapid temperature rise in the oil and theintake manifold due to the action of the turbocharger or supercharger.Likewise, the flow of TCF through the radiator will lessen any peakingof the engine block temperature. A short time after the turbocharger orsupercharger is deactivated, the EETC valve can then be returned to thestate dictated by the ECU.

Although the preferred embodiment of the invention employs a diaphragmvalve in valves 10 and 100, other types of hydraulically activatedchamber-type valves can be employed in place of the diaphragm valve. Oneparticularly suitable type of valve is a piston valve having a pistonhead which reciprocates within the bore of a piston housing, wherein thepiston head includes a piston shaft and a cup.

FIGS. 9 and 10 disclose one embodiment of a piston valve and FIGS. 11and 12 disclose another embodiment of a piston valve. Both types ofvalves provide a fluid flow passageway through at least a portion of thehousing when the valve is open and block off the fluid flow passagewaythrough that portion of the housing when the valve is closed. Both typesof valves employ the outer circumferential wall of their piston shaftsto block a fluid passageway opening through the housing, therebypreventing fluid flow through any portion of the housing. The valvesallow flow of fluid through the portion of the housing by moving theouter circumferential wall of their piston shafts wall away from theopening. The valve embodiment in FIGS. 11 and 12 is a flow-through typeof valve. That is, when the valve is open, the fluid controlled by thevalve flows through the interior of the piston head. In contrast, in theembodiment in FIGS. 9 and 10, the fluid does not flow through the pistonhead.

In both of the piston valve embodiments, the piston head is moved fromthe closed to the open position by the force of hydraulic fluid pressureagainst a rear surface of the cup, and is moved back to the closedposition by the force of a biasing spring, in a manner similar inprinciple to movement of the diaphragm valves in valves 10 and 100. Thehydraulic fluid enters and leaves the piston valve through a pair ofhydraulic fluid injectors in the same manner as in the valves 10 and100.

FIG. 9 shows a sectional side view of EETC valve 500 and FIG. 10 shows aright end view of the EETC valve 500 in FIG. 9. The solid lines in FIG.9 shows the EETC valve 500 in its first position which is associatedwith a valve "closed" state. FIG. 9 also shows the valve's secondposition in phantom which is associated with a valve "open" state. Forclarity, FIGS. 9 and 10 are described together.

The EETC valve 500 includes valve mechanism casing or housing 502,piston head 504, an inlet hydraulic fluid injector 18 and an outlethydraulic fluid injector 20. Only the inlet hydraulic fluid injector 18is visible in FIG. 9, whereas both injectors 18, 20 are visible in FIG.10. Injector 18 is connected to fluid inlet tube 36 and injector 20 isconnected to fluid outlet tube 38, in the same manner as the valves 10and 100.

The housing 502 is a generally cylindrical solid structure having a bore506 therethrough. The housing 502 is bolted closed at one end 508 bycover 510 and open at the other end 512. The housing 502 is defined byfive main parts, the cover 510, a first cylindrical portion 514 havingan inner diameter of about d₁, a second cylindrical portion 516 havingan inner diameter of about d₂ and two barrels 518, 520 extending fromthe housing 502, each barrel housing one of the fluid injectors 18, 20.Barrel 518 and injector 18 are visible in FIG. 9. Only the barrel 518 isvisible in FIG. 9, whereas both barrels 518, 520 are visible in FIG. 10.The diameter d₂ is larger than d₁.

The housing 502 also includes two openings therethrough. A first opening522 located in a mid-region of the first cylindrical portion 514 allowstemperature control fluid (TCF) from passageway 524 to pass therethroughwhen the first opening 522 is not obstructed by the piston head 504. Asecond opening (not shown) allows hydraulic fluid to flow into and outof a chamber 526 within the housing's second cylindrical portion 516, toand from the pair of fluid injectors 18, 20. Fluid pressure sensor 550is in communication with the chamber 526. The sensor 550 is visible inFIG. 10 but is not visible in FIG. 9. This sensor 550 performs the samefunction as the fluid pressure sensor 28 in the EETC valve 10.

The piston head 504 is a unitary solid structure defined by two mainparts, a piston shaft 528 and a piston cup 530 connected to one end ofthe shaft 528. The other end of the shaft 528 is closed. The piston cup530 and the left hand portion of the piston shaft 528 reciprocate withinthe second cylindrical portion 516 of the housing 502. The piston shaft528 is a preselected length which allows its outer circumferential wallto block the first opening 522 when the piston head 504 is in the firstposition and allows its outer circumferential wall to move completelyaway from the first opening 522 when the piston head 504 is in thesecond position. The piston shaft 528 has an outer diameter d₃ which isslightly less than d₁, thereby allowing the shaft 528 to fit tightlywithin the bore's first cylindrical portion 514. Likewise the piston cup530 has an outer diameter d₄ which is slightly less than d₂, therebyallowing the cup 530 to fit tightly within the bore's second cylindricalportion 516. The cup 530 has a rear surface 532 which faces the pistonshaft 528. The cup includes grooves 534 around its outer circumferentialsurface for seating piston O-rings 536 therein. Likewise, the innercircumferential surface of the bore's first cylindrical portion 514includes grooves 538 around its circumference for seating O-rings 540therein. The cup 530 also includes a cup-shaped insert 538 for holdingone end of biasing spring 542 therein.

The EETC valve 500 is biased in the closed position by the biasingspring 542 which is mounted at the one end to an inner surface of thecup's insert 538 and at the other end to an inner surface of the cover510. To hold the other end of the spring 542 in place, the cover 510includes knob 544 which extends perpendicularly into the bore 506 fromthe center of its inner surface, the other spring end being seatedaround the knob 544.

To move the EETC valve 500 from its first position to its secondposition, the valve associated with the fluid injector 18 is opened inresponse to a control signal from an ECU (not shown). Simultaneously,the valve associated with the fluid injector 20 is closed, if it is notalready closed. Pressurized hydraulic fluid from the fluid inlet tube 36flows through the injector 18 and into the chamber 526, where it pushesagainst the piston cup's rear surface 532. When the fluid pressureagainst the cup's rear surface 532 exceeds the opposing force of thebiasing spring 542, the piston head 504 moves to the left until itreaches the second position shown in phantom, thereby causing the pistonshaft 528 to move away from the first opening 522. The TCF in thepassageway 524 can now flow through the right hand portion of thehousing 502 and into the radiator. A pressure sensor (not shown) and theECU (not shown) cooperate in the same manner as described with respectto the EETC valve 10 to determine when to close the valve of thehydraulic fluid injector 20, thereby trapping the hydraulic fluid in thechamber 526. Thus, the piston shaft 528 will remain in the secondposition as long as the fluid injector valves remain closed. The O-rings536 and 540 prevent the hydraulic fluid in the chamber 526 from leakingout into other parts of the housing 502. Likewise, the O-rings 540prevent the TCF from leaking into other parts of the housing 502.

When it is desired to close the EETC valve 500, those steps arereversed. That is, the ECU sends a control signal to the solenoid of thehydraulic fluid injector 18 to close the injector's valve, if it is notalready closed. Simultaneously, the ECU sends a control signal to thesolenoid of the hydraulic fluid injector 20 to open that injector'svalve. The pressurized hydraulic fluid inside the chamber 526 flows outthrough the housing's second opening (not shown), through the open valveof the hydraulic fluid injector 20 and into the fluid outlet tube 38. Asthe hydraulic fluid empties out of the chamber 526, the biasing spring542 pushes the piston head to the right and into the first position,thereby causing the piston shaft 528 to block the first opening 522 andshut off fluid flow through the EETC valve 500. When the pressure sensor(not shown) detects that the chamber 526 is no longer pressurized, itcauses the ECU to send a control signal to the solenoid of the hydraulicfluid injector 20 to close that injector's valve.

FIGS. 11 and 12 show a flow-through version of a piston valve suitablefor use as an EETC valve. FIG. 11 shows a sectional side view of EETCvalve 600 and FIG. 12 shows a right end view of the EETC valve 600 inFIG. 11. The solid lines in FIG. 11 shows the EETC valve 600 in itsfirst position which is associated with a valve "closed" state. FIG. 11also shows the valve's second position in phantom which is associatedwith a valve "open" state. For clarity, FIGS. 11 and 12 are describedtogether.

The EETC valve 600 includes valve mechanism casing or housing 602,piston head 604, an inlet hydraulic fluid injector 18 and an outlethydraulic fluid injector 20. Only the inlet hydraulic fluid injector 18is visible in FIG. 11, whereas both injectors 18, 20 are visible in FIG.12. Injector 18 is connected to fluid inlet tube 36 and injector 20 isconnected to fluid outlet tube 38, in the same manner as the valves 10and 100.

The housing 602 is a generally cylindrical solid structure having a bore606 therethrough. The housing 602 is closed at one end 608 and open atthe other end 612. The housing 602 is defined by five main parts,including three cylindrical portions and two barrels. The threecylindrical portions are, from left to right, a first cylindricalportion 614 having an inner diameter of about d₁, a second cylindricalportion 616 having an inner diameter of about d₂ and a third cylindricalportion 617 having an inner diameter of about d₃. The diameter d₂ islarger than d₁ and the diameter d₃ is about the same as d₁. The firstcylindrical portion 614 is closed at the left end (which corresponds tothe closed housing end 608) and open at the right end. The second andthird cylindrical portions 616 and 617 are open at both ends. The rightend of the third cylindrical portion 617 corresponds to the open housingend 612. The third cylindrical portion 617 is a separate structuralpiece and is bolted to the second cylindrical portion 616 by an integralcircular flange 646. The left end of the third cylindrical portion 617extends slightly into the right end of the second cylindrical portion616. Two barrels 618, 620 extend from the housing 602, each barrelhousing one of the fluid injectors 18, 20. Barrel 618 and injector 18are visible in FIG. 9. Only the barrel 618 is visible in FIG. 11,whereas both barrels 618, 620 are visible in FIG. 12.

The housing 602 also includes two openings therethrough. A first opening622 located near the left end of the first cylindrical portion 614allows temperature control fluid (TCF) from passageway 624 to passtherethrough when the first opening 622 is not obstructed by the pistonhead 604. A second opening (not shown) allows hydraulic fluid to flowinto and out of a chamber 626 within the housing's second cylindricalportion 616, to and from the pair of fluid injectors 18, 20. Fluidpressure sensor 650 is in communication with the chamber 626. The sensor650 is visible in FIG. 12 but is not visible in FIG. 10. This sensor 650performs the same function as the fluid pressure sensor 28 in the EETCvalve 10.

The piston head 604 is a unitary solid structure defined by two mainparts, a hollow piston shaft 628 and a piston cup 630 connected to oneend of the shaft 628. Unlike the other end of the shaft 528 in thepiston head 504, the other end of the shaft 628 (i.e., the left end) isopen. Also, a center region of the piston cup 630 is hollow. The pistoncup 630 and the right hand portion of the piston shaft 628 reciprocatewithin the second cylindrical portion 616 of the housing 602. The pistonshaft 628 is a preselected length which allows its outer circumferentialwall to block the first opening 622 when the piston head 604 is in thefirst position and allows its outer circumferential wall to movecompletely away from the first opening 622 when the piston head 604 isin the second position. The piston shaft 628 has an outer diameter d₄which is slightly less than d₁, thereby allowing the shaft 628 to fittightly within the bore's first cylindrical portion 614. Likewise thepiston cup 630 has an outer diameter d₅ which is slightly less than d₂,thereby allowing the cup 630 to fit tightly within the bore's secondcylindrical portion 616. The cup 630 has a rear surface 632 which facesthe piston shaft 628. The cup includes grooves 634 around its outercircumferential surface for seating piston O-rings 636 therein.Likewise, the inner circumferential surface of the bore's firstcylindrical portion 614 includes grooves 638 around its circumferencefor seating O-rings 640 therein.

The EETC valve 600 is biased in the closed position by biasing spring642 which is seated at one end against the cup's inner surface 648, andat the other end around the outer circumference of the left end of thethird cylindrical portion 617. The far end of the spring's other endlies against the circular flange 646.

To move the EETC valve 600 from its first position to its secondposition, the valve associated with the fluid injector 18 is opened inresponse to a control signal from an ECU (not shown). Simultaneously,the valve associated with the fluid injector 20 is closed. Pressurizedhydraulic fluid from the fluid inlet tube 36 flows through the injector18 and into the chamber 626, where it pushes against the piston cup'srear surface 632. When the fluid pressure against the cup's rear surface632 exceeds the opposing force of the biasing spring 642, the pistonhead 604 moves to the right until it reaches the second position shownin phantom, thereby causing the piston shaft 628 to move away from thefirst opening 622. The TCF in the passageway 624 can now flow throughthe hollow interior of the piston head 604, through the right handportion of the housing 602 (i.e., the third cylindrical portion 617) andinto the radiator. The hydraulic fluid remains trapped in the chamber626 because the only outlet passageway, the valve of the hydraulic fluidinjector 20, is closed. Thus, the piston shaft 628 will remain in thesecond position as long as the states of the fluid injector valves arenot changed. The O-rings 636 and 640 prevent the hydraulic fluid in thechamber 626 from leaking out into other parts of the housing 602.Likewise, the O-rings 640 prevent the TCF from leaking into other partsof the housing 602.

When it is desired to close the EETC valve 600, those steps arereversed. That is, the ECU sends a control signal to the solenoid of thehydraulic fluid injector 18 to close the injector's valve.Simultaneously, the ECU sends a control signal to the solenoid of thehydraulic fluid injector 20 to open that injector's valve. Thepressurized hydraulic fluid inside the chamber 626 flows out through thehousing's second opening (not shown), through the open valve of thehydraulic fluid injector 20 and into the fluid outlet tube 38. As thehydraulic fluid empties out of the chamber 626, the biasing spring 642pushes the piston head 604 to the left and into the first position,thereby causing the piston shaft 628 to block the first opening 622 andshut off fluid flow through the EETC valve 600.

The hydraulic fluid flow paths in the EETC valves 500 and 600 differslightly from the paths in the EETC valves 10 and 100. In the EETCvalves 500 and 600, the hydraulic fluid does not flow through any commonpassages or passageways between the injectors and the valve chamber.Instead, each injector is in direct communication with the valvechamber. This feature is illustrated in FIGS. 10 and 12 by respectivephantom dashed lines 552 and 652 which extend from the fluid injectorsinto the valve chamber.

FIGS. 16A and 16B show a hydraulic fluid injector 700 in cross-sectionwhich is suitable for controlling the state or position of the EETCvalves in the invention. As noted above, the fluid injector 700 issolenoid activated and includes an electrical terminal 702 connected atone end to injector solenoid 704 and at the other end to an ECU (notshown). When the solenoid 704 is energized, it causes needle valve 706to move up, thereby moving it away from seat 708 and opening orifice 710to fluid flow. When the solenoid 704 is deenergized, biasing spring 712causes the needle valve 706 to return to the closed position.

FIG. 16A shows the inlet fluid flow path from a source of pressurizedhydraulic fluid, through the injector and to the valve chamber. Thevalve in this figure thus performs the function of the valve 18 in FIG.4. FIG. 16B shows the outlet fluid flow path from the valve chamber,through the injector and to a reservoir of hydraulic fluid. The valve inthis figure thus performs the function of the valve 20 in FIG. 4.

The fluid injector 700 is similar to a DEKA Type II bottom feedinjector, commercially manufactured by Siemens Automotive, Newport News,Va. Although this injector is typically employed to inject meteredquantities of gasoline into the combustion chamber of an engine, it canalso function as a valve to pass other types of hydraulic fluidtherethrough.

When the hydraulic fluid is engine lubrication oil, the Siemens typeinjector can be employed with only minor modifications such as anincreased lift or stroke (e.g., 0.016 inches, instead of 0.010 inches)and a larger flow orifice 710 (e.g., 0.060" .O slashed. area) forincreased flow capacity. The biasing spring 712 is preferably a heavyarmature spring to seal against up to 80 psi pressure in a reverseposition. The needle valve 706 preferably includes a 3% silicon ironarmature 707 to obtain the appropriate lift. The metal housing of theinjector is slightly modified and arranged to allow for twist snap-inassembly. The O-rings are smaller and relocated to be on the valve body.Also, since engine oil is not as corrosive as gasoline, internalcomponents of the Siemens type injector do not need to be plated.Furthermore, the filter associated with commercially available injectorsis not employed.

The inlet fluid injector 700 is preferably operated in a reverse flowpattern. That is, fluid flows through the inlet injector 700 in anopposite direction as the injector is normally employed in a gasolineengine. When the inlet injector 700 is operated in this manner, pressurefrom the valve chamber tends to seal the needle valve 706 against itsseat 708, thereby lessening the tendency of the injector 700 to leak.This also ensures that the EETC valve remains open during engine off"hot soak" if conditions warrant an open state.

FIG. 16C shows an alternative type of hydraulic fluid injector 800 incross-section which is suitable for controlling the state or position ofthe EETC valves in the invention. The injector 800 is similar to a DEKAType I top feed injector, commercially manufactured by SiemensAutomotive, Newport News, Va. In this type of injector, the hydraulicfluid flows through the entire length. Although FIG. 16C shows bothfluid flow paths through the same injector 800, only one injector 800 isemployed for each path. The injector 800 is also preferably operated ina reverse flow pattern and without a filter. This type of injector has anumerous advantages over the DEKA Type II injector.

When employing the injector 800 in an EETC valve, the top of theinjector 800 is connected directly to the EETC valve's upper chamber,not to a common passage. This allows for more versatile packagingconfigurations because the inlet and outlet injectors do not need to bephysically near each other. It also reduces the amount of retainedtrapped air in the EETC valve, potentially eliminating the need to bleedout trapped air when filling the chamber. The injector 800 is alsosmaller and cheaper than the injector 700. One disadvantage of this typeof injector is that it is more difficult to get hydraulic fluid such asoil to flow smoothly therethrough.

FIG. 17 shows a block diagram circuit of the connections to and from ECU900 for controlling the state or position of the EETC valves. Thepreferred embodiment of the ECU 900 receives sensor output signals fromat least the following sources:

1. an ambient air sensor in an air cleaner (clean side) or othersuitable location;

2. a temperature sensor at the end of the engine block's (or the inletto the cylinder head) temperature control fluid water jacket;

3. a pressure sensor in the engine block's temperature control fluidwater jacket;

4. a temperature sensor in the engine block oil line;

5. a pressure sensor in the engine block oil line; and

6. a pressure sensor in the EETC valve's hydraulic fluid passageway.

The ECU 900 utilizes some or all of those sensor signals to generateopen/close command signals for the fluid injectors of the EETC valve. Asnoted above, the hydraulic fluid pressure signals are also employed todetect unsafe operating conditions. The engine oil fluid pressure signalcan be employed to detect unsafe operating conditions and/or todetermine when the oil lubrication system is sufficiently pressurized toallow for proper operation of the EETC valve.

A typical control routine for opening a diaphragm type EETC valve sizedto replace a prior art wax pellet or bimetallic coil type thermostat andemploying fluid injectors connected to the engine lubrication oil systemis as follows:

1. If engine is being started, wait appropriate amount of time untilengine oil is adequately pressurized. It will typically take two tothree seconds to allow it to reach a minimum pressure of 40 psi.

2. Activate solenoid of inlet fluid injector to open its valve. (Closevalve of outlet fluid injector, if it is not already closed.)

3. Wait until chamber pressure (as measured by the fluid pressuresensor) reaches about 25 psi.

4. Activate a two second timer in the ECU.

5. After two seconds, deactivate the solenoid of the inlet fluidinjector to close its valve.

6. If the fluid pressure sensor detects a pressure drop below 25 psi,repeat steps 2-5.

If the engine oil is warm, the total time to complete steps 2-5 will beabout six seconds. If the engine oil is cold, step 2 will take longer,thereby lengthening the total time.

The ECU 900 can also perform other emergency control functions tomaintain the TCF in a safe range. For example, in extremely hot ambientair conditions, the temperature of the TCF might exceed a safe range,even if the EETC valve is fully open. In typical prior art vehicles, anoverheating condition will be signalled to the driver through adashboard mounted engine warning light or the like. The novel systemshown in FIG. 17 can respond to this condition by temporarily openingthe heater core valve and/or shutting off the vehicle's air conditioningsystem. The first of these measures will assist in removing excess heatfrom the engine block. The second of these measures will reduce the loadon the engine, thereby reducing its heat energy output. If thesemeasures still fail to reduce the temperature of the TCF to a saferange, the system can then activate the engine warning light. Anotherdashboard mounted light can indicate when the ECU has taken emergencycontrol of the vehicle's climate control system.

Likewise, in extremely cold, sub-zero ambient air temperatures, theheater core valve can be automatically deactivated or restricted toavoid draining heat energy from the engine block until the temperatureof the TCF reaches an acceptable minimum level.

One example of how the ECU 900 controls the state or position of an EETCvalve based on specific parameters is described in FIGS. 19-21 of thisdisclosure, and will be discussed in more detail hereinbelow.

FIG. 18 diagrammatically shows the flow path of the TCF diverted fromthe passageway 156 in FIG. 7. When the EETC valve 100 is in its firstposition, at least a portion, if not all, of the TCF in the passageway156 flows through the opening 158 and into the passageway 160. Thepassageway 160 is connected to one end of passage 802 drilled throughthe engine block. The other end of the passage 802 is connected to theinlet end of the heat conductive tube 220 inside the engine block oilpan 94. The passage 802 is sealed at both ends by O-rings 804 to preventleakage of the TCF into the oil pan 94. The O-rings 804 also function toinsulate the passage 802 from the oil pan 94 and the passageway 160.Alternatively, if drilling a passage through the engine block is notpractical or desired, the passageway 160 and the inlet end of the tube220 can be connected to ends of an insulated tube exterior to the engineblock. The outlet end of the heat conductive tube 220 is connected to apassageway leading to the water pump inlet (not shown). The tube 220 issecured inside the oil pan 94 by hanger 806 attached to the engineblock. The hanger 806 is insulated to prevent it from conducting heatenergy from the tube 220 into the engine block. The hanger 806 alsocushions the tube 220 from engine vibrations. Suction through the tube220 is enhanced by placing the outlet end close to the water pump inlet.

The passageway 160 can also lead to other passages and tubes disposed inother engine parts, thereby allowing the TCF to warm or heat those otherparts too. For example, additional TCF passages can lead to tubesdisposed in the reservoir of the automatic transmission, the brakesystem's master cylinder or ABS system, windshield washer fluid or thelike. The TCF would then flow to these parts whenever it flows to theoil pan. Alternatively, flow to one or more of these parts can becontrolled by a separate flow control valve so that when the TCF flowsto the oil pan, the fluid selectively flows to desired parts inaccordance with different temperature parameters.

The EETC valves described herein are designed to replace the prior artwax pellet type or bimetallic coil type thermostat. These thermostatsare typically located in an opening connecting a radiator inlet passageto an outlet of an engine water jacket. Accordingly, the EETC valves aredimensioned to fit into that opening. Likewise, the EETC valve housingincludes holes to allow the valves to be mounted in that opening in thesame manner as the prior art thermostats are mounted within the engine.Thus, the EETC valves can be retrofitted into existing engine TCFpassageways. The only additional apparatus required to install the EETCvalve 10, 500 and 600 are the hydraulic fluid lines and electrical wiresfor connection to the inlet and outlet hydraulic fluid injectors. Theselines and wires can be placed inside the engine compartment whereverspace permits. To install the EETC valve 100, the TCF passageway must beslightly modified to provide the extra passageways 160 and/or 216 showndiagrammatically in FIGS. 14A through 14F and FIG. 18. Likewise, if theEETC valve 100 is employed to control the intake manifold flow controlvalve 300 and/or the cylinder head valve 400, the fluid outlet tube 174must be provided from the EETC valve 100 to the valve 300, as shown inFIG. 8.

Notwithstanding the above discussion of the valve location, the EETCvalve can alternatively be located wherever it can properly perform thefunction(s) attributed thereto. Likewise, the EETC valve can have othersizes which are appropriate for its alternative location.

The EETC valves are suitable for any form of internal combustion enginewhich opens and closes an engine block TCF passageway to a radiator.Thus, both gasoline and diesel engine environments are within the scopeof the invention.

Although the hydraulic fluid which controls the state or position of theEETC valve is preferably engine oil, it can be any type of pressurizedhydraulic fluid associated with a vehicle powered by an internalcombustion engine. In one alternative embodiment, the hydraulic fluid ispower steering fluid wherein the source of the pressurized hydraulicfluid is the high pressure line of a power steering pump. The hydraulicfluid emptied from the EETC valve flows into the power steering fluidreservoir. In this embodiment, the power steering pump is modified sothat it provides high pressure at all times. That is, high pressure canbe tapped from the pump when the wheel is not being turned and when theengine is off, in addition to when the wheel is being turned. Also, thisversion employs a prior art pressure regulating valve in the highpressure line to achieve a constant output pressure of about 10 to about120 psi, regardless of the varying input pressure of the power steeringunit, which can range up to 1000 psi. In this manner, the EETC valve isnever exposed to pressures exceeding about 120 psi, regardless of theoutput pressure of the power steering unit.

In another alternative embodiment, a separate hydraulic fluid systemoperates the EETC valve. This embodiment would require many componentsto be uniquely dedicated to the task, such as a separate hydraulic pump,and thus would significantly increase the cost of the system.

The invention also contemplates the use of alternate means forcontrolling the EETC valve, although these may not be preferred. Forexample, TCF fluid could be fed to a separate pump which pressurizes thefluid. The pressurized TCF is then fed into the injectors for actuatingthe diaphragm. In yet another embodiment of the invention, anelectro-mechanical servo could actuate the valve member 146. Thoseskilled in the art would readily appreciate the variations that arepossible within the scope of this invention.

Dead heading or restricting TCF flow through portions of the waterjacket reduces heat loss from the engine block. It also reduces the massof TCF circulating through the water jacket, thereby raising thetemperature of the circulating mass above what it would be if the masswas larger. Both of these effects allows the engine block to warm upmore quickly. As noted above, heat energy is primarily transferred toand from the engine block by the flow of fluid. Therefore, dead headingor restricting the flow will have almost the same effect as shutting offthe flow. Since dead heading or restricting TCF flow effectively trapsall or part of the TCF in the dead headed or restricted passageway, thetrapped TCF acts as an insulator. That is, the hot fluid in the waterjacket prevents the engine heat from readily dissipating to theenvironment. This is due, primarily, to the fact that the TCF is abetter insulator than a conductor. Accordingly, this insulating functionfurther reduces heat loss from the engine block.

Some of the preferred materials for constructing the EETC valve andoperating parameters were described above. In one embodiment of theinvention, the following materials and operating parameters were foundto be suitable for a diaphragm type EETC valve.

Biasing spring--stainless steel

Valve housing and cover--glass filled nylon injection molded ispreferred, aluminum is also acceptable

Wall thickness of diaphragm valve body and cover--0.090 inches

Air bleed opening--0.060 inches diameter

Valve rod--cored out to obtain uniform thickness for injection molding

Diaphragm stroke--up to one inch

U-shaped tube in oil pan--two feet length, or more

Minimum valve operation pressure--20 psi (i.e., valve will open at 20psi.). This will be sufficient for most engines which operate withengine lubrication oil pressures in the range from about 37 psi. (at thelowest idle speed) to about 75 psi.

Maximum valve operation pressure--120 psi.

The ECU 900 can be programmed with specific information to control thestate of the EETC valves and any restrictor/shutoff valves 300 and/or400 associated therewith.

FIGS. 19 and 20 show one example of how the ECU 900 is programmed withinformation to control the state of an EETC valve based upon thetemperature of the TCF and the ambient air temperature, whereas FIG. 21shows the state of prior art wax pellet type or bimetallic coil typethermostats within the same ranges of temperatures.

Turning first to FIG. 21, prior art wax pellet type or bimetallic coiltype thermostats are factory set to open and close at a preselectedcoolant temperature. Thus, the state of these thermostats are notaffected by the ambient air temperature. That is, no matter how cold theambient air temperature becomes, these thermostats will open when thecoolant temperature reaches the factory set value. A thermostat designedfor use in a cooling system employing a permanent type antifreeze (asopposed to an alcohol type antifreeze) is typically calibrated to openat about 188 to about 195 degrees Fahrenheit and be fully open betweenabout 210 to about 212 degrees Fahrenheit.

Since the EETC valves in the invention are computer controlled, theirstates can be set to optimize engine temperature conditions over a widerange of ambient air temperatures and TCF temperatures. In oneembodiment, the ECU 900 in FIG. 17 is programmed with the curve shown inFIG. 19. The curve is defined by a two-dimensional mathematical functionof t1=ƒ(t2), where t1 is the temperature of the TCF in the engine blockand t2 is the ambient air temperature, t1 and t2 being axes on anorthogonal coordinate system. The curve divides the coordinate systeminto two regions, one on either side of the curve.

In operation, the ECU 900 continuously monitors the ambient airtemperature and the TCF temperature to determine what state the EETCvalve should be in. If coordinate pairs of these values lie in region 1of the FIG. 19 graph, the EETC valve is closed (or remains closed if itis already in that state). Likewise, if coordinate pairs of these valueslie in region 2, the EETC valve is opened (or remains open if it isalready in that state). If coordinate pairs lie exactly on the curve,the ECU is programmed to either automatically select one of the tworegions or to modify one or both of the values so that the coordinatepair does not lie exactly on the curve.

Alternately, the state of the EETC valve could be controlled simplybased on the actual engine oil temperature. In such an embodiment, theactual engine oil temperature would be compared to a predeterminedoptimum engine temperature as a function of the ambient temperature, asshown in FIG. 25. When the actual engine oil temperature is colder thanthe desired/optimum temperature, the EETC valve could be closed therebyraising the engine temperature. Similarly, if the actual engine oiltemperature is higher than the desired/optimum temperature, the EETCvalve could be opened, thereby circulating the TCF through the radiatorto cool it down. One deficiency with using the engine oil temperature asa controlling factor is the lag time involved in bringing the oil to aprescribed temperature. Additionally, there are upper and lowertemperature limits on the TCF that should not be exceeded in currentautomobile cooling systems. Therefore, it is preferable to control theoperating state of the EETC valve through the monitoring of ambient airtemperature and the TCF temperature.

The curve shown in FIG. 19 has been experimentally determined to provideoptimum engine temperature control in a typical internal combustionengine when an EETC valve replaces the typical prior art thermostatsdescribed above. However, the curve can be different, depending upon thedesired operating parameters of the engine and its accessories. Anengine employing an EETC valve which is controlled according to thecurve in FIG. 19 will have lower emissions, better fuel economy and amore responsive vehicle climate control system than the same engineemploying the thermostat. These improvements will be greatest in thelower ambient temperature ranges.

To illustrate some advantages of the EETC system, consider a vehiclewhich is first started up when the ambient air temperature is zerodegrees Fahrenheit. Until the coolant or TCF temperature reaches about188 degrees Fahrenheit, the prior art system in FIG. 21 and the EETCsystem in FIG. 19 will both prevent the coolant or TCF from flowingthrough the radiator. However, when the coolant temperature exceedsabout 188 degrees Fahrenheit, the prior art system will open thethermostat and allow either some or virtually all of the coolant to flowthrough the radiator, thereby lowering the coolant temperature. Thisreduces the ability of the vehicle's heater/defroster to deliver hot air(i.e., heat) to the vehicle interior and windows because the coolantflowing through the heater core will be cooler than if it did not flowthrough the radiator. Furthermore, this also unnecessarily removesvaluable heat energy from the engine block.

When the ambient temperature is zero degrees Fahrenheit, typicalinternal combustion engines often do not need to be cooled by coolantflow through the water jacket since the ambient air presents asignificant heat sink. Furthermore, when the ambient air temperature isabout zero degrees Fahrenheit, the heat energy emitted by enginecombustion often does not raise the oil temperature or the engine blockabove the level desired for safe and optimum operation. In fact, insub-zero ambient air temperatures, the engine block of a typicalinternal combustion engine will have an average temperature of less than150 degrees Fahrenheit which is less than the ideal operatingtemperature. Accordingly, high oil viscosity and sludge build-up, whichincreases emissions and lowers fuel economy, are virtually unavoidableconditions when operating engines having prior art thermostat controlledcooling systems in sub-zero ambient air temperatures.

Consider the same vehicle operating in the same ambient temperatureenvironment with an EETC valve system. As shown in FIG. 19, the EETCvalve will remain closed until the TCF exceeds about 260 degreesFahrenheit, a condition that might not even occur unless the engine isdriven very hard and/or fast. Consequently, the TCF flowing through theengine water jacket will not unnecessarily remove valuable heat energyfrom the engine block and engine lubrication oil. Furthermore, the TCFflowing through the heater core will become hot more quickly and willremain hotter than the coolant in the FIG. 21 scenario, therebyresulting in improved defrosting and vehicle interior heatingcapabilities.

In a control system employing the curve in FIG. 19, the EETC valve canbe any of the valves described in the invention. If the EETC valve isemployed in conjunction with one or more of the restrictor/shutoff flowcontrol valves 300 or 400, the curve can be slightly modified to obtainoptimum temperature control conditions. Specifically, the portion of thecurve between about 58 to about 80 degrees Fahrenheit in FIG. 19 canhave the same slope as the portion of the curve between about 60 degreesto about zero degrees Fahrenheit, as shown in FIG. 20.

When the EETC valve is employed in conjunction with the additional flowcontrol valves, emission levels will even be lower, fuel economy evengreater, and the vehicle climate control system even more responsivethan the system employing only the EETC valve. If the EETC valve 100 isemployed in the system, hot ETC will flow through the oil pan atvirtually all times when the ambient air temperature is zero degreesFahrenheit. This will improve the oil viscosity and reduce engine sludgebuild-up.

When the EETC valve is employed in conjunction with the intake manifoldflow control valve 300, engine performance improvements will occur inhigh temperature environments as a result of avoiding excessive heatingof the intake manifold, as discussed above with respect to the system inFIGS. 14A through 14C.

When the EETC valve is employed in conjunction with flow control valvesassociated with the cylinder head and/or cylinder block, as discussedabove with respect to FIGS. 14A through 14C, very precise tailoring ofengine temperature can be achieved. For example, when the ambienttemperature is very low and the EETC valve is closed, the one or moreflow control valves are likewise closed to restrict and/or dead head theTCF that would ordinarily flow through certain portions of the engineblock. Preferably, the TCF is allowed to flow only through the hottestportions of the engine block, such as areas of the cylinder head jacketclosest to the cylinders. This achieves at least two desired effects.First, the TCF flowing through the limited portions of the engine waterjacket will not unnecessarily remove valuable heat energy from theengine block and engine lubrication oil. Second, the limited amount ofthe TCF which exits the water jacket will be hotter than if the TCFflowed through all parts of the engine block. Thus, the TCF flowingthrough the heater core will become hot more quickly and will remainhotter than if the TCF flowed through all parts of the engine block,thereby resulting in improved defrosting and vehicle interior heatingcapabilities.

FIG. 22A shows a valve state graph which employs a curve similar to thecurve in FIG. 20 but which employs the valve states to control the stateof the EETC valve and two restrictor/shutoff valves. In region 1, theEETC valve is closed and the restrictor/shutoff valves are in anrestricted/blocked state. In region 2, the EETC valve is open and therestrictor/shutoff valves are in an unrestricted/unblocked state.

FIG. 23 graphically shows a dotted curve of the actual temperature ofthe temperature control fluid measured in an engine block of a GM 3800transverse engine equipped with an EETC valve and two restrictor/shutoffvalves when the state of the valves are controlled according to the FIG.22A scheme. The restrictor/shutoff valves are located on either side ofa V-shaped engine block in the outer TCF flow passages around thecylinder liner, and together restrict the flow through the engine blockby about 50 percent in their fully restricted state. FIG. 23 also showsa dashed curve of the actual temperature of engine coolant measured inthe engine block when a prior art wax pellet type or bimetallic coiltype thermostat is employed and its state determined according to theprior art FIG. 21 scheme.

The prior art thermostat operates to try to maintain a constant coolanttemperature in a range from about 180 to about 190 degrees Fahrenheit.However, when the ambient air temperature is very hot (e.g., 100 degreesFahrenheit), the coolant temperature will exceed the desired range evenif the thermostat is fully open. This is because the ability of thevehicle's cooling system to cool the coolant is dependent upon thecapacity of the radiator. It is usually impractical and too expensive toinstall a radiator large enough to maintain temperatures below 200degrees Fahrenheit at all times. Thus, regardless of the type of flowcontrol valves employed in the vehicle's engine, coolant temperatureswill exceed the optimal range in hot weather conditions.

In very cold ambient temperatures such as sub-zero temperatures, thecoolant temperature in the prior art system will be below the desiredrange and will continue to decrease with decreasing ambient airtemperatures. This will cause a significant decrease in fuel economy anda significant increase in exhaust emissions for all of the reasonsdiscussed above. Sludge formation will also be a significant problem.

The system employing the EETC valve and restrictor/shutoff valves showan improved TCF temperature curve because it maintains the TCFtemperature more closely to the optimum range throughout a greaterambient temperature range. When the ambient air temperature is very hot(e.g., 100 degrees Fahrenheit) and full flow through the radiator hasbegun, the TCF temperature will be slightly less than the coolanttemperature in the prior art system, mainly as a result of the greaterflow allowed through the EETC valve, as compared to the prior art waxpellet type thermostat. However, the cooling capability of the system inthe invention will still be limited by the fixed capacity of theradiator.

In cold ambient air temperatures, especially sub-zero temperatures, thesystem in the invention maintains the TCF temperature at valuessignificantly higher than the coolant temperature in the prior artsystem. This is because the restrictor/shutoff valves have been placedin the state where they restrict or shut off a portion of flow throughthe engine block. This flow restriction reduces the heat energy lossfrom the engine block, thereby allowing the limited amount of flowingTCF to reach a greater temperature. The engine block heat energy loss isreduced in at least two ways. First, less mass of TCF flows through thewater jacket so less heat energy is transferred to the TCF where it islost to the atmosphere. Second, the restricted and/or trapped TCF actsas an insulator around portions of the engine block. Since the limitedamount of flowing TCF is at a greater temperature than the prior artcoolant, the TCF improves the operating capability of the vehicleinterior heater and defroster. Furthermore, since the engine operates ata hotter temperature, engine out exhaust emissions are lower, fueleconomy is greater than in the prior art system. Also, sludge is lesslikely to form in the engine.

Instead of controlling the state of the EETC valve andrestrictor/shutoff valves in accordance with the curve shown in FIG.22A, the EETC valve and restrictor/shutoff valves can be controlledaccording to separate curves, as shown in FIG. 22B. By employingseparate curves, the flow of TCF can be more precisely tailored toachieve a more optimum actual TCF temperature in FIG. 23. At very highambient air temperatures, the EETC valve should normally be fully openand the restrictor/shutoff valves should normally be fullyunrestricted/unblocked. At very low ambient air temperatures, the EETCvalve should normally be fully closed and the restrictor/shutoff valvesshould normally be fully restricted/blocked. However, it may be moredesirable for ideal engine operating conditions to keep one or both ofthe restrictor/shutoff valves open in mid-temperature ranges, even afterthe EETC valve has closed. FIG. 22B shows a region 3 wherein these dualstates are achieved. In one embodiment of the invention, a TCFtemperature differential of about 15 degrees Fahrenheit is employed.

A system employing the curves shown in FIG. 22B will allow therestrictor/shutoff valve(s) to open or unblock the TCF passagewayshortly before the EETC valve opens flow to the radiator at a givenambient air temperature. One advantage of this system is that thetemperature of the TCF circulating through the engine block's waterjacket will become more homogeneous by opening the restrictor/shutoffvalves before the EETC valve is opened, thereby improving the overallaccuracy of the system in determining when to open the EETC valve. Thisis because the total TCF mass will be heated to the desired programmedtemperature (as determined by the EETC valve curve) before TCF flow isintroduced to the radiator. Time delays can be incorporated to preventthe EETC and/or restrictor valve from oscillating between open andclosed positions. Alternately, additional curves could be utilized aswill be discussed below.

When the restrictor/shutoff valves are in their restricted or blockedposition, the temperature TCF in different portions of the engine blockcan vary significantly. For example, if the fluid in the outer waterjacket passageways is dead headed, it will be colder than the fluid inthe inner water jacket passageways. When the restrictor/shutoff valvesare opened, the hotter and colder fluids immediately begin to mix,thereby reducing the variation in temperature of the TCF in differentportions of the water jacket. Thus, as the TCF continues to heat up, themeasured TCF temperature, which determines when to open the EETC valve,will be more accurate.

Some engines, like the GM 3800 V-6 engine, utilize a random pattern ofopenings to connect the waterjackets between the engine block and thecylinder head. Accordingly, the restrictor/shutoff flow control valvesmust be properly located so as to restrict or block the continuous flowpath between the block and the cylinder head so as to maintain a mass ofTCF in the block for faster warm up. Alternately, the enginewaterjackets themselves could be designed to operate with the EETC valveto provide additional efficiency. An example of such an embodiment isillustrated in FIGS. 44A and 44B, and designated generally as 1400,wherein two individual waterjacket flow paths are incorporated into theengine, 1402 and 1404, respectively. The waterjackets are schematicallyshown external to the associated engine components for sake of clarity.However, it should be understood that the waterjackets are, preferably,integral with the engine components. One flow path 1402 would be thenormal waterjacket path from the water pump 1406 through the engineblock 1408 into the cylinder head 1410 and intake manifold 1412. Thesecond waterjacket 1404 would flow from the water pump 1406 directly tothe cylinder head 1410, intake manifold 1412, heater/defroster circuit(not shown), and engine oil pan 1414, by-passing the engine block 1408.An EETC valve as described hereinabove or, alternately, a rotary valve1416 would be incorporated to direct the TCF between the twowaterjackets depending on the operational state of the engine.

FIG. 44A illustrates the novel system during engine warm-up. The EETCvalve 100 is in its closed position, inhibiting TCF flow to theradiator. Hence, substantially all the TCF is directed to the intakemanifold and the oil pan 1414 where it exchanges heat with the oil. TheTCF is then directed through the water pump 1406 to a second controlvalve 1416. Control valve 1416, during warm-up, is in a state whereinpreferably all the TCF is directed along the by-pass waterjacket 1404into the cylinder head 1410 and intake manifold. Waterjacket 1402 is,effectively, blocked, thereby trapping a mass of TCF within the engineblock. The TCF flowing through the by-pass waterjacket 1404 into thecylinder head will quickly increase in temperature since there is lessmass being exposed to the heat of the cylinder heads. Meanwhile, the TCFtrapped in the engine block 1408 will function as an insulator,preventing unneeded heat loss and, consequently, resulting in lowerexhaust emissions, better fuel economy and quicker heater/defrostercapabilities. Restrictor valves may be incorporated between the cylinderhead 1410 and the intake manifold 1412 (similar to FIGS. 14E and 14F).These valves may be actuated to prevent or reduce TCF flow therethroughwhen the TCF reaches a predetermined temperature which may have anadverse effect on the combustion of the fuel, as described above.Alternately, and more preferably, the EETC valve 100 controls the TCFflow into the intake manifold, as well as, the oil pan.

Restrictor valves (not shown) may also be incorporated between theengine block 1408 and the cylinder head 1410 to inhibit the flow of TCFbetween the two during warm-up. However, the continuous flow of the TCFthrough the by-pass water jacket 1404 will obstruct the passage of TCFfrom engine block 1408 to the cylinder head 1410. Accordingly, dependingon the design of the waterjacket, restrictor valves may not be required.

The last portion of the Background of the Invention describes that theprior art technique of controlling internal engine temperature solely bycontrolling engine coolant temperature is crude and inaccurate. TheBackground of the Invention also describes how this technique oftencauses overheating or overcooling of the engine, even when the coolanttemperature is maintained at a predesired level. The invention describedin FIGS. 19-23 significantly reduces the amount of engine overheatingand overcooling.

To even more accurately control the internal engine temperature, theinvention described in FIGS. 19-23 may be modified to employ two or moredifferent curves for controlling the state of the EETC valve and therestrictor/shutoff valves. The appropriate curve is selected bycomparing the actual engine oil temperature to a preselected engine oiltemperature value. In the preferred embodiment of the invention, thepreselected value is a temperature associated with optimum internalengine performance (e.g., the temperature which maximizes fuel economyand minimizes engine out exhaust emissions). In one embodiment of theinvention, this value may be fixed. However, in the preferred embodimentof the invention, this value is related to the current ambient airtemperature.

Selecting between different curves further improves the performance ofthe engine temperature control system because the state of the EETCvalve and restrictor/shutoff valves becomes more responsive to theactual internal engine temperature (as measured by engine oiltemperature) rather than when only a single curve is employed forcontrolling each of the valves.

FIG. 24 is generally similar to FIG. 20, except that FIG. 24 shows threeEETC valve curves, a solid line "Normal Curve", a dotted "High LoadCurve", and an Xed line "Extreme High Load Curve." The "Normal Curve" isgenerally similar to the curve shown in FIG. 20. However, the curves inFIG. 24 are based upon empirical data for the GM 3800 transverse engine.Thus, the "Normal Curve" in FIG. 24 differs slightly from the curveshown in FIG. 20, which is not necessarily optimized for that engine. Tosimplify the explanation of the multiple curve embodiments, the valvestates and regions are not labelled in the multiple curve figures.) Thestate of the EETC valve is controlled in accordance with the "NormalCurve" whenever the actual engine oil temperature is at or below apreselected engine oil temperature. The state of the EETC valve iscontrolled in accordance with the heavy load or "High Load Curve"whenever the actual engine oil temperature exceeds the preselectedengine oil temperature. The state of the EETC valve is controlled inaccordance with the "Extreme High Load Curve" whenever there is afrequent rate of shifting between the "Normal Curve" and the "High LoadCurve." Such frequent shifting indicates that the EETC valve is closingtoo often to maintain the desired engine oil temperature, as furtherexplained below.

The "Normal Curve" will typically be employed when the vehicle is drivenunder light load conditions. This will occur approximately 80% of thetime. The "High Load Curve" will typically be employed during theremaining time. Heavy load conditions may occur when a vehicle is drivenat high speed, when the vehicle is fully loaded or pulling a trailer, orwhile climbing a mountain in hot ambient air temperatures.

The "High Load Curve" may have the same overall general appearance asthe "Normal Curve," except that the "High Load Curve" is shifted downfrom the "Normal Curve" by about 50 degrees Fahrenheit. Likewise, the"Extreme High Load Curve" may have the same overall general appearanceas the "High Load Curve," except that the "Extreme High Load Curve" isshifted down from the "High Load Curve" by about 20 degrees Fahrenheit.

The preselected engine oil temperature is a value associated with thepreferred operating temperature of the engine. Each engine has anoptimum operating temperature for maximizing performance (i.e.,horsepower output), maximizing fuel economy and minimizing engine outexhaust emissions. The optimum operating temperature may be differentfor each of these parameters, although the optimum temperature formaximizing fuel economy tends to be similar to that for minimizingemissions. The examples described herein focus primarily on fuel economyand emissions, not engine performance. Thus, the preselected valuedescribed herein is one which optimizes internal engine performance asdefined by fuel economy and engine out exhaust emissions. However, atlow temperatures, a system with the EETC valve and restrictors shouldalso generate increased engine horsepower.

In one embodiment of the invention, this value is fixed. That is, asingle optimum engine oil temperature is selected which results in thegreatest fuel economy and the lowest engine out exhaust emissions forthe most frequently encountered ambient air temperature. In thisembodiment, the actual engine oil temperature (as measured in the oilpan) is compared to the preselected optimum value. The result of thecomparison is employed to select the appropriate curve, as describedabove.

In the preferred embodiment of the invention, the preselected value isnot fixed. Instead, it is dependent upon the current ambient airtemperature. The Background of the Invention explains that as theambient air temperature declines, the internal engine components loseheat more rapidly to the environment. Also, there is an increasedcooling effect on the internal engine components from induction air. Tocounter these effects and thus maintain the internal engine componentsat the optimum operating temperature, the engine oil should be hotter incold ambient air temperatures than in hot ambient air temperatures. Theoptimum engine oil temperature can be plotted against the ambient airtemperature based on empirical data and known engine specifications. Todetermine the preselected optimum value for use in the comparison, thecurrent ambient air temperature is measured and the optimum engine oiltemperature is selected based on the value indicated on the plot.

FIG. 25 shows one such empirically determined plot for a GM 3800transverse engine. The plot shows that the optimum engine oiltemperature increases as the ambient air temperature decreases. The plotin FIG. 25 may be shifted upwards or downwards when the vehicle isoperating in high or low altitudes. Empirical testing of each engine inhigh and low altitude conditions is required to determine whether theplot will be shifted upwards or downwards. Of course, the plot will beslightly different if a specific parameter is more important (e.g., fueleconomy, engine out exhaust emissions, engine performance). Hence, it ispossible to vary the curve shown in FIG. 25 during a typical engineoperation. For example, the ECU could receive signals indicating that alarge sudden increase in acceleration has been commanded, e.g.,significant depression of gas pedal on entering a highway. Accordingly,the curve could be altered or changed to a curve which provides higherperformance with less emphasis on fuel economy. Those skilled in the artwould readily appreciate the variations to the system that could bepracticed within the scope of this invention.

As noted in the Background of the Invention, engine coolant temperaturerises more rapidly than the internal engine temperature during enginestart-up or warm-up. Since the prior art thermostat is actuated bycoolant temperature, it often opens before the internal enginetemperature has reached its optimum value, thereby causing coolant inthe water jacket to prematurely cool the engine. As described above,exhaust emissions from cold running engines are a major source of airpollution. For example, a delivery truck or taxi operating in a cityenvironment during the cold weather season ordinarily covers shortdistances at slow speed and makes frequent stops. Accordingly, theengine seldom gets hot enough to drive the water and vapor out of thecrankcase resulting in the formation of sludge. In order to prevent thesludge from forming in the oil it is desirable to maintain the engineoil at an elevated temperature. However, prior art thermostats are setto open at about 195 degrees Fahrenheit which, during start-up,corresponds to an engine oil temperature which is considerably below thedesirable temperature for preventing sludge. Furthermore, opening thethermostat and permitting low temperature coolant to flow into theengine block slows the heating of the oil. This results in a "slowing"effect in obtaining the optimum engine oil temperature value.

By employing the novel EETC valve and a special curve during enginestart-up, the optimum engine oil temperature value is reached soonerthan with a prior art thermostatic system. As a result, the engine oiloperates at or near its optimum temperature value for a longer period oftime during engine operation. Moreover, the maintenance of engine oil ata higher temperature for a longer period of engine operation, almostentirely prevents the formation of sludge in the crankcase and oil pan.The quicker heat-up of the oil also provides improved engine out exhaustemissions during warm-up and in cold environments thereby providingsignificant environmental benefits. As an added benefit, the quickerheat-up of the engine greatly improves the vehicle heater/defrosterresponsiveness and effectiveness. An engine operating at or near optimumtemperature will also have better fuel economy when compared with a coldrunning engine. Hence, the EETC and restrictor valves, in combinationwith the operational curves, provide an optimum system for controllingengine performance. Whenever the engine is started, no heat will escapethrough the radiator until the TCF temperature reaches its maximumoperational level (e.g., approximately 240° F. to 250° F. range) andremains at that temperature level until the engine oil, preferably asmeasured in the oil pan, reaches and sustains its optimum runningtemperature.

FIG. 26 shows two EETC valve curves, a "Normal Curve" similar to thatshown in FIG. 24, and a "Start-Up/Warm-Up Curve." The "Start-Up/Warm-UpCurve" is generally similar to the "Normal Curve," except that the"Start-Up/Warm-Up Curve" has a "bump-up" region from about 110 degreesFahrenheit to about 20 degrees Fahrenheit. The bump-up region has amaximum bump-up of about 65 degrees Fahrenheit when the ambient airtemperature is about 85 degrees Fahrenheit. The bump-up becomes smalleras the ambient air temperature approaches about 20 degrees Fahrenheit.The maximum bump-up is about 50 degrees Fahrenheit compared to the priorart thermostat.

During engine start-up or warm-up, the engine oil will almost always becolder than the optimum temperature. Thus, in most situations, the"Start-Up/Warm-Up Curve" will be employed during initial vehicleoperation. Once the engine oil reaches its optimum temperature, asdetermined by FIG. 25, the system switches to the "Normal Curve." Inrare instances, the initial engine oil temperature will be at or greaterthan the optimum temperature during engine start-up. This may occur ifthe engine is only shut off for a few seconds, or if the engine isstarted shortly after a period of heavy loading. In these instances, theEETC valve is operated according to the "Normal Curve", instead of the"Start-Up/Warm-Up Curve".

The inventions illustrated in FIGS. 24 and 26 are preferably employed inthe same system. Thus, the EETC valve actually follows at least threecurves during vehicle operation, one curve during warm-up/start-up, onecurve during normal operation subsequent to warm-up/start-up, and onecurve during high load conditions subsequent to warm-up/start-up. Afourth curve for extreme high load conditions may be included, ifdesired.

Although FIGS. 24 and 26 illustrate the operation of an EETC valve, therestrictor/shutoff valves are also controlled in a similar manner.Preferably, the restrictor/shutoff valves follow their own curves, asshown in FIG. 22B. These curves are shifted down versions of the EETCvalve curve. If this feature was shown in FIG. 24, there would be atotal of four curves. The extra curve would represent the normal curvefor the restrictor/shutoff valves. (There will be no high load curve forthe restrictor/shutoff valves because in a high load condition, therestrictor/shutoff valves should be fully retracted.) FIG. 26 would showa total of four curves (excluding the prior art curve). The two extracurves in that figure would represent the normal curve and thestart-up/warm-up curve for the restrictor/shutoff valves. Forsimplicity, this feature is merely described, but not illustrated.

FIG. 27 is a flowchart of the system for employing the start-up/warm-upcurve, normal curve and high load curve of FIGS. 24 and 26. The steps inthe flowchart are fully explained in the discussion above.

FIG. 28 shows a block diagram circuit of the connections to and from ECU900 for controlling the state or position of the EETC valve. FIG. 28 isgenerally similar to FIG. 17, except that the ECU 900 in FIG. 28processes the received sensor output signals according to the flowchartin FIG. 27. The ECU 900 may also receive an altitude signal for shiftingthe plot in FIG. 25 upwards or downwards when the vehicle is operatingin a high altitude. FIG. 28 does not show the hydraulic fluid pressuresignals and engine oil fluid pressure signal in FIG. 17. However, thesefeatures may be optionally included in a full operating embodiment ofFIG. 28.

The ECU 900 in FIG. 28 preferably receives sensor output signals from atleast the following sources:

1. an ambient air sensor in an air cleaner (clean side) or othersuitable location;

2. a temperature sensor at the end of the engine block's temperaturecontrol fluid water jacket, or other suitable location;

3. an oil temperature sensor in the engine oil pan;

4. an altitude sensor; and

5. an optional "High Engine Load" sensor.

The ECU 900 utilizes some or all of those sensor signals to generateopen/close command signals for the fluid injectors of the EETC valve.Although FIGS. 27 and 28 do not describe the operation of therestrictor/shutoff valves, it should be understood that these valves arealso operated in accordance with the same principles as the EETC valve.

An added benefit of a system utilizing the multiple curves discussedabove is that the time between oil changes can be increased. Frequentoil changes become necessary when the internal engine temperature is notmaintained at its optimum value during a significant percentage ofdriving time. The multiple curve system reduces this percentage, therebyprolonging the life of the oil.

FIG. 29 graphically shows the benefit of operating an engine inaccordance with multiple curves. FIG. 29 shows a solid line plot of theoptimum engine oil temperature at selected ambient air temperatures.(This is the same plot shown in FIG. 25.) FIG. 29 also shows a dashedline plot of the actual temperature of the engine lubrication oilmeasured in the oil pan of a GM 3800 transverse engine equipped with anEETC valve when the state of the EETC valve is controlled according tothe curves shown in FIGS. 24 and 26. (No "Extreme High Load Curve" isemployed in the system which generates the plots in FIG. 29.) Forcomparison, FIG. 29 also shows a dashed/dotted plot of the actualtemperature of the engine lubrication oil when coolant flow to theradiator is controlled by a prior art thermostat calibrated to open atabout 195 degrees Fahrenheit.

When the ambient air temperature is less than about 60 degreesFahrenheit, the EETC valve system significantly outperforms the priorart thermostat. That is, the EETC valve system maintains the actualengine oil temperature closer to the optimum value. When the ambient airtemperature is greater than about 70 degrees Fahrenheit, the capacity ofthe radiator limits the ability of the cooling system to maintain theengine oil temperature at its optimum value. Thus, no matter what kindof flow control valve is employed, the engine oil will run hotter thandesired. However, as is shown in FIG. 29, an engine incorporating thepresent invention will still operate closer to the optimum engine curveat higher temperatures compared to the prior art thermostatic system.This is due to the better flow capacity provided by the EETC valve,i.e., 50% more flow capacity than a restrictive thermostat. The EETCvalve of the present invention also opens up sooner when operating inhotter temperatures than the thermostatic system and, therefore,maintains the engine at the coolest possible operating temperature (asshown in FIG. 24).

When the ambient air temperature is in a sub-zero degree Fahrenheitrange, a prior art thermostat allows engine oil temperature to dip intoa sludge forming range of temperatures. This occurs because the coolanttemperature may reach a level sufficient to cause the prior artthermostat to open, even when the internal engine temperature issignificantly below its optimum operating value.

FIG. 29 also shows an Xed line plot which represents actual engine oiltemperature in a system employing an EETC valve, restrictor/shutoffvalves and an oil pan tube for delivering heat to the engine oil. Such asystem maintains actual engine oil temperature very close to the optimumvalue, even in sub-zero Fahrenheit ambient air temperatures. In ambientair temperatures above about zero degrees Fahrenheit, the plot of such asystem generally follows the plot of a system employing only the EETCvalve.

FIG. 30 shows a trend line of TCF temperature and oil temperature duringvehicle operation (and after engine start-up/warm-up). In this example,the ambient air temperature is about 40 degrees Fahrenheit. According tothe FIG. 25 plot, the optimum engine oil temperature at this temperatureis about 240 degrees Fahrenheit.

From time t₀ to t₁, the engine is operating under low load conditionsand thus is following the "Normal Curve" in FIG. 24. The actual TCFtemperature is about 220 degrees Fahrenheit. The EETC valve is closed,as dictated by the "Normal Curve." The actual engine oil temperature isabout 238 degrees Fahrenheit, as expected from FIG. 29.

At time t₁, the vehicle engine begins to experience high loadconditions. Almost immediately, the engine oil heats up and exceeds theoptimum value in FIG. 25. Accordingly, the system shifts to the "HighLoad Curve" in FIG. 24. This causes the EETC valve to open, therebyallowing the TCF to flow to the radiator. Between times t₁ and t₂, theTCF temperature drops quickly and stabilizes at a lower value of about180 degrees Fahrenheit. During this time period, the lower TCFtemperature causes the engine oil temperature to slowly drop after itsquick rise. At time t₂, the engine oil temperature returns to 238degrees Fahrenheit and the system shifts back to the "Normal Curve."This causes the EETC valve to close. Between times t₂ and t₃, the TCFtemperature rises slowly. Between times t₂ and t₃, the engine oiltemperature may continue to drop slowly and then rise due to a lag timeuntil the warmer TCF begins to heat the oil. Eventually, the engine oiltemperature stabilizes at 238 degrees Fahrenheit.

After time t₃, the trend lines repeat themselves so long as the highload condition is still present. Thus, the system cycles between the"Normal Curve" and the "High Load Curve." If the system is equipped withthe optional "Extreme High Load Curve," the frequency of cycling istracked. If the frequency is too high, the system begins to switchbetween the "Normal Curve" and the "Extreme High Load Curve," andignores the "High Load Curve." If the high load condition ceases, thesystem returns to the "Normal Curve" and the engine oil and TCFtemperatures stabilize at the time t₀ values.

Although the multiple curve embodiments rely on engine oil temperatureto determine when to switch curves, other internal engine temperatureparameters may be employed instead and are within the scope of theinvention. For example, a thermistor embedded in the engine block can beemployed to obtain a more accurate reading of the actual engineoperating temperature.

FIGS. 31A and 31B illustrates a novel optional oil heating feature forthe system described in FIGS. 24-30. FIG. 31A is an idealizeddiagrammatic view of the TCF circulation flow path through a GM 3800 V6transverse engine equipped with an EETC valve in the closed state. FIG.31A is similar to prior art FIG. 40, except that the prior artthermostat 1200 in FIG. 40 is replaced with EETC valve 100. Also, inFIG. 31A, the outlet of the water jacket 1202 does not flow directlyinto the inlet of the water pump 1206, as in FIG. 40. Instead, theoutlet of the water jacket 1202 flows into TCF flow path 1300. Thisconfiguration was previously discussed with respect to FIGS. 14A through14F. Hence, TCF flow path 1300 corresponds to passageway 216 in thosefigures. The TCF flow path 1300 flows through oil pan 1302 and into theinlet of the water pump 1206 in a series manner. Thus, preferably all ofthe TCF which leaves the water jacket 1202 flows through the oil pan1302 before it is returned to the water pump 1206 for recirculation. TheTCF flow path 130 includes heat conductive tube 1304 which is similar tothe heat conductive tube 220 shown in FIG. 18. For illustration purposesonly, FIG. 31 exaggerates the length of the conductive tube 1304 and thesize of the oil pan 1302.

In operation, preferably all of the TCF at the outlet of the waterjacket 1202 flows through the heat conductive tube 1304 whenever theEETC valve 100 is closed. During engine start-up/warm-up, the EETC valve100 is usually closed and the internal engine temperature is most likelycolder than the optimum value. Since the TCF temperature in the waterjacket 1202 rises more rapidly than engine oil temperature during enginestart-up/warm-up, heat energy from the hotter TCF in the conductive tube1304 is transferred to the engine oil in the oil pan 1302, therebypromoting faster engine warm-up.

FIG. 31B illustrates the temperature control system of FIG. 31A when theEETC valve 100 is in the open position. Substantially all of the TCF istransferred through the valve to the radiator 208. However, a smallamount of TCF may still transfer through the intake manifold to the oilpan if the EETC valve is designed so that it does not completely blockthe flow therethrough.

FIGS. 32A and 32B illustrate an alternate embodiment of the temperaturecontrol system wherein the TCF can be utilized to cool the engine oil.FIG. 32A is an idealized diagrammatic view of the TCF circulation flowpath through a GM 3800 V6 engine equipped with an EETC valve in theclosed state and is similar to FIG. 31A. FIG. 32B illustrates the valvein its open state which completely obstructs the passage of the TCF intothe intake manifold and the oil pan. Accordingly, all of the TCF willflow through the radiator 208 in this state.

Turning again to FIG. 30, when the engine experiences high loadconditions and the engine oil exceeds its optimum value, the systemshifts to the "High Load Curve." If the EETC valve 100 is not alreadyopen, it will most likely open, resulting in a relatively quick andsharp drop in the TCF temperature. If the TCF in the TCF flow path 1300is cooler than the engine oil, the TCF circulating through theconductive tube 1304 will draw heat away from the engine oil, promotingengine oil cooling. This will shorten the time period between t₁ and t₂in FIG. 30.

There may be instances when the EETC valve 100 is open and the engineoil temperature is already at or near the optimum value. In thisinstance, flow through the flow path 1300 is not desirable because itwill cause unnecessary cooling of the engine oil. Although the flow path1300 in FIG. 32A does not include a flow control valve, such a valve maybe employed to ensure that flow only occurs when the engine oiltemperature exceeds the optimum value.

An added benefit of the extra flow path 1300 is that the heat energy inthe TCF transfers to the oil pan 1302 when the engine is off. This helpsto keep oil temperatures above sludge forming conditions when thevehicle is not in use. The system shown in FIGS. 32A and 32B also willresult in a more uniform temperature differential throughout the entiresystem, thereby resulting in a lower temperature of the TCF than theoil.

The EETC valve described herein can be employed with one or morerestrictor/shutoff flow control valves to improve the temperaturecontrol function of the system over that which would be achieved whenemploying only the EETC valve, with or without its optional oil panheating feature. As noted above, the restrictor/shutoff flow controlvalves 300 and 400 shown in FIG. 14A can be any type suitable for thetask. However, one type of novel restrictor/shutoff flow control valveparticularly suitable for this task is disclosed in FIGS. 33-39. Thenovel valve, labelled as 1000 in the figures, shares manycharacteristics with the flow-through piston type EETC valve 600described with respect to FIG. 11, including the following similarities:

1. The state or position of the flow control valve 1000 is controlled bythe position of a reciprocating piston mechanism.

2. The position of the reciprocating piston mechanism is controlled bypressurized hydraulic fluid in a valve chamber and a biasing spring.

3. The hydraulic fluid enter and exits the valve chamber through a pairof hydraulic fluid injectors.

FIG. 33 is a diagrammatic sectional view of a typical prior art fourcylinder engine block showing three flow control valves 1000₁, 1000₂ and1000₃ which restrict TCF flow through portions of engine block TCFpassageways 1002₁, 1002₂ and 1002₃, respectively, and one flow controlvalve 1000₄ which blocks TCF flow through intake line 1003 associatedwith an intake manifold. (The outtake line associated with the intakemanifold is not visible in this view.) The manner in which a flowcontrol valve 1000 blocks flow, as opposed to restricting flow, is bestillustrated with respect to FIG. 38, described below. In one embodimentof a system shown in FIG. 14A, the flow control valve 300 is similar tothe flow control valve 1000₄, whereas the flow control valve 400 isequivalent to one of the flow control valves 1000₁, 1000₂ and 1000₃.

FIG. 33 also shows EETC valve 1006 for controlling flow of the TCF tothe radiator, and heater control valve 1008 for controlling flow of theTCF to the heater core. The state or position of the EETC valve 1006 andthe flow control valves 1000₁, 1000₂, 1000₃ and 1000₄ are controlled byhydraulic fluid injector pairs 1010, as described above. FIG. 33 onlyshows one pair of hydraulic fluid injectors 1010 which simultaneouslycontrols the state of the flow control valves 1000₁, 1000₂ and 1000₃.The state of the flow control valve 1000₄ may be controlled by aseparate pair of injectors 1010 (not shown), or may be controlled by theinjectors associated with the EETC valve 1006 (not shown). The pair ofinjectors 1010 shown in FIG. 33 includes fluid inlet tube 1012 connectedto a source of pressurized hydraulic fluid 1014 and fluid outlet tube1016 connected to hydraulic fluid reservoir 1018. In this embodiment,the source of pressurized hydraulic fluid 1014 is engine lubrication oilfrom an oil pump, whereas the hydraulic fluid reservoir 1018 is the oilpan.

FIGS. 34 and 35 show a preferred embodiment of the restrictor/shutoffvalve 1000. FIG. 34 shows a sectional side view of the valve 1000mounted in a TCF passageway. The solid lines in FIG. 34 show the valve1000 in a first position which is associated with a valve "open" orunrestricted/unblocked state. FIG. 34 also shows, in phantom, the valve1000 in a second position which is associated with a valve "closed" orrestricted/blocked state. FIG. 35 shows an exploded view of the parts ofthe valve 1000. For clarity, FIGS. 33, 34 and 35 are described together.

The restrictor/shutoff valve 1000 includes, among other parts, valvemechanism casing or housing 1020, piston 1022, reciprocating shaft 1024and piston valve seal or plug 1026. An inlet/outlet tube 1028 attachedto the rear of the housing 1020 is in fluid communication with the pairof the hydraulic fluid injectors 1010 associated with the valve 1000. Ifthe valve 1000 is not controlled by the remote pair of injectors 1010(as shown in FIG. 33), the injectors 1010 are part of the valve 1000itself. The pair of hydraulic fluid injectors 1010 are similar to theinjectors 18, 20. The housing 1020 is a generally cylindrical solidstructure having a bore 1030 therethrough. The bore 1030 has a generallyuniform inner diameter of d₁. The housing bore 1030 is partially closedat left end or near end 1032 by circular plate 1035, described in moredetail below. Circular mounting flange 1038 extends perpendicularlyoutward from the outer circumferential walls of the housing's near end1032. The mounting flange 1038 includes a plurality of holes 1040therethrough for receiving a series of bolts 1042 which attach the valve1000 to solid wall 1046 surrounding first passageway 1048. Gasket 1049is disposed between the mounting flange 1038 and the outer facingsurface of the wall 1046. When the valve 1000 is employed in theenvironment described herein, the solid wall 1046 is either part of anengine block or intake manifold surrounding a TCF passageway.

The housing bore 1030 is closed at right end or far end 1034, except foropening 1036 therethrough. One end of the inlet/outlet tube 1028 isattached to the housing opening 1036, thereby placing the hydraulicfluid injectors 1010 in fluid communication with the housing bore 1030.

The piston 1022 and reciprocating shaft 1024 are disposed in the bore1030 and have generally uniform outer diameters of d₂ and d₃,respectively. Diameters d₂ and d₃ are generally equal, and are slightlyless than d₁, thereby allowing the piston 1022 and reciprocating shaft1024 to fit tightly in the bore 1030. The piston 1022 includes front orleft outer facing surface 1050 and rear or right outer facing surface1052. The piston 1022 also includes grooves around its outercircumferential surface for seating O-rings 1054 therein. It is alsocontemplated that the O-rings 1054 could be configured similar to seal136 and O-ring 138 shown in FIG. 13A. The reciprocating shaft 1024 is agenerally cylindrical hollow solid structure which is open at left endor near end 1056 and closed at right end or far end 1058. The shaft'sfar end 1058 has an outer facing surface 1060 and an inner facingsurface 1062. The outer facing surface 1060 lies adjacent to, and incontact with the piston's left outer facing surface 1050. The shaft 1024includes four cut-outs along a near end or leftmost portion of itslongitudinal axis. One cut-out 1064 is labelled in FIG. 35. The cut-outs1064 are equally spaced around the shaft's outer circumference. In thismanner, the cut-outs 1064 form four fingers 1068 from that portion ofthe shaft's outer circumferential wall. Each finger 1068 has an endsurface 1069 with shouldered edges 1094.

Biasing spring 1070 is disposed inside of the hollow reciprocating shaft1024. One end of the spring 1070 lies against the shaft's inner facingsurface 1062 and the other end of the spring 1070 lies against an innerfacing surface of the circular plate 1035.

The plate 1035 includes four cut-outs 1072 therethrough which have thesame general shape as the shaft finger's end surfaces 1069 as they wouldappear without the shouldered edges 1094. The location of the cut-outs1072 match the location of the fingers 1068 when the finger's endsurfaces 1069 are adjacent to the plate 1035. Furthermore, the cut-outs1072 are slightly larger than the finger's end surfaces 1069 (withoutthe shouldered edges 1094) so that the fingers 1068 can reciprocallyslide through the cut-outs 1072, and thus through the plate 1035.

The piston valve plug 1026 also includes four cut-outs 1075 therethroughwhich also have the same general shape as the shaft finger's endsurfaces 1069. The location of the cut-outs 1075 match the location ofthe fingers 1068 when the finger's end surfaces 1069 are adjacent to theplug 1026. The cut-outs 1075 are slightly larger than the end surfaces1069 to allow the end surfaces 1069 to fit snugly therein. The cut-outs1075 function as attachment locations for welding or mechanicallystaking the fingers 1068 to the plug 1026.

During valve assembly, the shaft's fingers 1068 are slid through theplate 1035. Then, the end surfaces 1069 of the shaft's four fingers 1068are welded or mechanically staked to the piston valve plug 1026 at thecut-out locations 1075. The shouldered edges 1094 of the finger endsurfaces 1069 prevent the fingers 1068 from pushing through the cut-outs1075 and facilitate attachment of the fingers 1068 to the plug 1026.

The valve 1000 is biased in the first position (i.e., valve "open" orunrestricted/unblocked state) by the biasing spring 1070. In thisposition, the force of the spring 1070 biases the reciprocating shaft1024 in its rightmost position within the housing bore 1030. The lengthof the shaft 1024 and valve housing 1020 is such that in the firstposition, the shaft 1024 is fully retracted into the housing 1020 andthe inner facing surface of the plug 1026 lies adjacent to the outerfacing surface of the housing plate 1035, and in the second position,the outer facing surface of the plug 1026 lies adjacent to far wall 1071of the first passageway 1048. Also, in the first position, the piston1022 is in its rightmost position within the bore 1030, and in thesecond position, the piston 1022 is in its leftmost position within thebore 1030. In the embodiment shown in FIG. 34, the bore 1030 includes asmall amount of space, labelled as chamber 1074, between the piston'sright outer facing surface 1052 and the bore's far end 1034.

To move the valve 1000 from its first position to its second position,the valve associated with the inlet fluid injector of the pair ofhydraulic fluid injectors 1010 is opened in response to a control signalfrom an ECU (not shown). Simultaneously, the valve associated with theoutlet fluid injector of the pair of fluid injectors 1010 is closed.Pressurized hydraulic fluid from the fluid inlet tube 1012 flows throughthe inlet fluid injector of the pair 1010, through the tube 1028 andinto the chamber 1074, where it pushes against the piston's rear outerfacing surface 1052. When the fluid pressure against the piston's rearsurface 1052 exceeds the opposing force of the biasing spring 1070, thepiston 1022 moves to the left, pushing the shaft 1024 along with ituntil the piston 1022 and the shaft 1024 reach the second position shownin phantom. This movement causes the shaft's fingers 1068 to move intothe first passageway 1048, thereby partially restricting the flow of TCFtherethrough.

FIG. 34 represents unrestricted flow of TCF through the first passageway1048 by straight arrow lines and represents restricted flow by dashedsquiggly arrow lines. When the valve 1000 is in the second position, theflow of TCF is only partially restricted because the TCF can still flowthrough the shaft's cut-outs 1072 (i.e., between the fingers 1068)and/or around the shaft 1024. The percentage of restriction flow isdetermined by a plurality of factors, including the following fourfactors:

1. The total area of the cut-outs 1072.

2. The total number of valves 1000 in the first passageway 1048.

3. The extent that the shaft 1024 projects into the first passageway1048.

4. The area, if any, between the outer circumferential surface of theshaft 1024 and the inner circumferential wall of the first passageway1048 when the valve 1000 is in the second position.

If the valve 1000 is employed as a two-position valve which is either ina first or second position, only the first two factors will be relevantto the percentage of restriction.

After the valve 1000 is placed in the second position, the hydraulicfluid in the chamber 1074 remains trapped therein because the onlyoutlet passageway, the valve of the outlet hydraulic fluid injector ofthe pair 1010 is closed. Thus, the shaft 1024 will remain in the secondposition as long as the states of the fluid injector valves are notchanged. The O-rings 1054 prevent the hydraulic fluid in the chamber1074 from leaking out into other parts of the housing bore 1030, whilealso preventing the TCF (which may find its way into the housing bore1030 and hollow shaft 1024 through the plate's cut-outs 1072) fromleaking into the chamber 1074.

When it is desired to close the valve 1000, those steps are reversed.That is, the ECU sends a control signal to the solenoid of the inlethydraulic fluid injector in the pair 1010 to close the injector's valve.Simultaneously, the ECU sends a control signal to the solenoid of theoutlet hydraulic fluid injector of the pair 1010 to open that injector'svalve. The pressurized hydraulic fluid inside the chamber 1074 flows outthrough the housing's opening 1036, into the tube 1028, through the openvalve of the outlet hydraulic fluid injector and into the fluidreservoir 1018. As the hydraulic fluid empties out of the chamber 1074,the biasing spring 1070 pushes the shaft 1024 and piston 1022 to theright and back into the first position, thereby causing the shaft'sfingers 1068 to retract out of the first passageway 1048.

The chamber filling and emptying procedure is the same as describedabove with respect to the EETC valves. For brevity's sake, thisprocedure is not repeated herein. However, it should be understood thatthe valve 1000 shown in FIG. 34 is only one of a plurality of similarvalves which are all connected to a single pair of hydraulic fluidinjectors 1010. Only a single pressure sensor is required for eachgrouping of valves connected to a common pair of injectors 1010. Thus,the valve 1000 shown in FIG. 34 relies upon a pressure sensor in anothervalve in this grouping for a measurement of its chamber pressure. Sincethe tube 1028 is in fluid communication with the other valve chambers,it is also in fluid communication with that pressure sensor. If it isdesired to operate the valve 1000 in FIG. 34 independent of othervalves, a pressure sensor and separate pair of injectors 1010 would beassociated with the valve 1000.

FIG. 36 is a sectional view of the valve 1000 in FIG. 34, taken alongline 36--36 in FIG. 34. This view shows, from the center outward, thehousing plate 1035, biasing spring 1070, four shaft fingers 1068,housing 1020, bolts 1042 and solid wall 1046.

FIG. 37 is a sectional view of the valve 1000 in the second positionshown in FIG. 34, taken along line 37--37 in FIG. 34. However, the valve1000 represented by FIG. 37 has an oval shaped plug 1026' instead of theround plug shown in FIGS. 34 and 35. This view shows, from the centeroutward, the four shaft fingers 1068, plug 1026' and passageway far wall1071. FIG. 37 highlights an important feature of the invention, that theplug 1026' can be shaped and sized to seat against a far wall 1071having any shape or size. That is, the plug 1026' can have any desiredfootprint. Thus, although the plug 1026 shown in FIGS. 34 and 35 is acylindrical disk, it need not have that shape.

Water jacket passageways and TCF passageways around an intake manifoldtypically include odd shaped bends, curves and the like which cannot beeasily dead headed or blocked by simple-shaped plugs. The novel valve1000 described herein accepts an infinite variety of plug sizes andshapes, as long as the plug 1026 includes a region for welding ormechanically staking the end surfaces 1069 of the shaft's four fingers1068 thereto. Furthermore, while the four shaft fingers 1068 form thecorresponding flow channels for the TCF in the preferred embodiment,different numbers and configurations of the flow channels arecontemplated by the present invention. Also, the shape of the channelscould be configured to direct the flow in a prescribed pattern, e.g.,smooth or turbulent flow, flow to the right or left, etc.

FIG. 38 shows a sectional side view of valve 1000' mounted to solid wall1046' in first passageway 1048'. FIG. 38 illustrates how the valve 1000'can be employed for the dual function of restricting the firstpassageway 1048', while simultaneously dead heading or blocking a secondpassageway 1076.

This embodiment of the restrictor/shutoff valve is not controlled byremote pairs of fluid injectors. Instead, the fluid injectors areattached to housing 1020' in a manner similar to the integral fluidinjectors associated with the EETC valves 500 and 600. In the sectionshown in FIG. 38, one of the pair of fluid injectors 1010' (the inletinjector) is visible. FIG. 38 also shows fluid pressure sensor 1090' fordetecting the fluid pressure in the valve chamber 1074'. The valve 1000'also includes an optional opening 1092' for allowing the pair of fluidinjectors 1010' to be in fluid communication with chambers of othervalves 1000 or 1000'. In this manner, the pair of fluid injectors 1010'controls the state of these other valves.

In FIG. 38, the first and second positions of the valve 1000' arerepresented by solid and phantom lines, in the same manner as shown inFIG. 34. When the valve 1000' is in the first position, both passagewaysare unblocked and unrestricted by the valve's shaft 1024. When the valve1000' is in the second position, the first passageway 1048' isrestricted by the shaft's fingers 1068 and the second passageway 1076 isblocked by the plug 1026.

Alternatively, the plug 1026 may have openings (not shown) therethroughto allow a portion of the TCF in the second passageway 1076 to pass intothe first passageway 1048'. In this embodiment, the valve 1000'functions as a restrictor/restrictor valve (i.e., it restricts, but notblock the flow of TCF in the first and second passageways). The valve1000' could also be designed to prevent transfer of the fluid past therestrictor in the first passageway 1048', yet permit fluid transfer fromthe first passageway 1048' to the second passageway 1076.

The major purpose of the restrictor/shutoff valves 1000 are to block orreduce the flow of TCF through TCF passageways. As shown in FIG. 38, thenovel valve 1000 can simultaneously restrict flow through onepassageway, while blocking or dead heading flow through a differentpassageway. This simultaneous restricting/dead heading function isparticularly useful when one or more valves 1000 are employed in theengine block water jacket to selectively control flow of TCF through"interior" and "exterior" water jacket passageways. "Interior"passageways, as defined herein, are those which are associated withinterior most regions of the engine block water jacket, whereas"exterior" passageways, as defined herein, are those which areassociated with exterior most regions of the water jacket. In a typicalengine, the interior passageways are closest to the engine's movingparts. Consequently, those passageways are typically closest to the oillines which lubricate those moving parts and are closest to the hottestparts of the engine block.

Page 169 of the Goodheart-Willcox Automotive Encyclopedia, TheGoodheart-Willcox Company, Inc., South Holland, Ill., 1995, notes thatthe heat removed by the cooling system of an average automobile atnormal speed is sufficient to keep a six-room house warm in zero degreeFahrenheit weather. Although this passage refers to an operating modewhere the thermostat is open and flow to the radiator is permitted, itis clear that tremendous quantities of heat energy are generated by anaverage automobile, even when the coolant is not hot enough to open thethermostat. Internal combustion engines manufactured today fail to takefull advantage of such heat energy, especially in cold ambienttemperature environments.

In such cold ambient temperature environments (e.g., sub-zerotemperatures), it is most important to retain heat energy in theinterior passageways to keep the oil temperature within its optimumrange. It is also desirable to remove some heat energy from the interiorso that the heater/defroster and intake manifold receive some warm orhot TCF. Furthermore, it is desirable to reduce the heat energy lossfrom the exterior passageways so that valuable heat energy from theengine block is not wasted to the atmosphere. The valve 1000 is ideallysuited to perform this task.

FIG. 39 is a simplified diagrammatic sectional view of the water jacketin engine block 1078 showing two interior passageways 1080, two exteriorpassageways 1882 and valves 1000₁, 1000₂ for respectively dead headingand restricting those passageways. That is, each valve 1000₁ and 1000₂blocks flow through an exterior passageway 1082 and simultaneouslyrestricts flow through an interior passageway 1080. In the embodimentshown in FIG. 39, the valve 1000₁ blocks flow through the lower exteriorpassageway, whereas the valve 1000₂ dead heads the flow through theupper exterior passageway. As noted above, dead heading the flow allowsthe TCF fluid trapped in the passageway to function as an insulator,further reducing undesired heat energy loss from the engine block 1078to the ambient environment.

FIG. 39 thus shows how the valve 1000' shown in FIG. 38 is employed in awater jacket wherein the first passageway 1048' is equivalent to aninterior passageway and the second passageway 1076 is equivalent to anexterior passageway.

Some of the preferred materials for constructing the restrictor/shutoffvalve and operating parameters were described above. In one embodimentof the invention, the following materials and operating parameters werefound to be suitable.

Biasing spring--stainless steel

Valve housing--aluminum die casting--machined or stainless steel sheetmetal

Shaft, plug--powdered metal or aluminum die cast

Piston/shaft stroke--aluminum die casting--machined or stainless steelsheet metal

Flow restriction--variable from about 50 percent to about 100 percent

Although the pair of hydraulic fluid injectors 1010 associated with therestrictor/shutoff valves may be similar to the injectors 18, 20, thepreferred inlet fluid injector will most likely require a larger flowcapacity than the inlet fluid injector 18. Likewise, the fluid inlettube 1012 will also most likely require a larger flow capacity than thefluid inlet tube 36 associated with the injector 18.

The larger flow capacity may be required because the restrictor/shutoffvalve will usually be operated (i.e., moved into a restricted or blockedposition) in much lower ambient air temperatures than the EETC valve. Ifengine lubrication oil is employed as the hydraulic fluid, such oil willhave a higher viscosity in a cold temperature environment. When the oilis thick and slow flowing, the valve chamber will fill more slowly thanwhen the oil is at a higher temperature, and thus at a lower viscosity.If the ambient air temperature is very low (e.g., sub-zero degreesFahrenheit), the filling time could become unacceptably long. Byincreasing the flow capacity through the inlet injector and into thechamber, the filling time is decreased to compensate for the higherviscosity oil.

To increase the flow capacity through the inlet fluid injector whenemploying a fluid injector such as the DEKA Type II injector shown inFIG. 16A, the orifice 710 should be increased. Also, the lift of theneedle valve 706 should be greater. The greater lift will probablyrequire a greater capacity solenoid 704.

The outlet fluid injector associated with the restrictor/shutoff valveis only opened when the valve is moved into an unrestricted or unblockedposition. Since this will normally occur only after the engine haswarmed up and the oil viscosity has decreased, this injector and itsassociated outlet tube need not necessarily be designed to handle agreater flow capacity. Likewise, since the chamber of the EETC valve isfilled (thereby allowing TCF fluid flow to the radiator) only when theengine and engine oil are relatively hot, the injectors 18, 20 willusually not encounter this flow capacity problem either.

The slow filling of the valve chamber caused by high oil viscosity willnot be a problem in prolonged extremely cold temperature environments(e.g., prolonged sub-zero degree Fahrenheit temperatures). In suchconditions, it is entirely possible that the restrictor/shutoff valvewill remain in a restricted or blocked position for days or weeks at atime without being moved into its unrestricted/unblocked state.

The restrictor/shutoff valves can be employed in an anticipatory mode tolessen the sudden engine block temperature peaks caused when aturbocharger or supercharged is activated, in the same manner as theanticipatory mode described above with respect to the EETC valves. Whenthe turbocharger or supercharger is activated, a signal can beimmediately delivered to the restrictor/shutoff valves to cause thevalves to be placed in their unrestricted/unblocked state, if they arenot already in that state. A short time after the turbocharger orsupercharger is deactivated, the valves can then be returned to thestate dictated by the ECU.

In extremely hot ambient air conditions, a system wherein the states ofthe EETC valve and restrictor/shutoff valves are controlled according toone or more of the curves will perform better upon engine start-up thana cooling system having a thermostat controlled solely by coolanttemperature. This is because the curves allow the designer to anticipateexpected engine operating conditions based on the present TCF andambient air temperature. Accordingly, the EETC valve can be immediatelyopened and the restrictor/shutoff valves can be immediately placed in anunblocked/unrestricted state in anticipation of an expected engineoperating condition that would call for such states.

Consider, for example, a prior art vehicle which has been sitting in thesunlight when the ambient air temperature is 100 degrees Fahrenheit. Insuch an environment, the underhood and vehicle interior is likely to beat least 120 degrees Fahrenheit. The coolant temperature will likely beat least 100 degrees Fahrenheit. When the driver enters the vehicle andstarts the engine, the air conditioning is typically immediately turnedon to its maximum setting. Due to the hot conditions and the extrastress on the engine due to the air conditioning system, the coolanttemperature quickly rises. Although it is virtually certain that thecoolant will need to flow to the radiator to keep the engine block at anoptimal operating temperature, the thermostat must nevertheless waituntil the temperature has reached the appropriate level before it opensto allow flow to the radiator. The result is that full engine cooling istemporarily delayed. If the vehicle is equipped with a prior art waxpellet type or bimetallic coil type thermostat, there will an evengreater delay before the coolant can flow to the radiator due tothermostat hysteresis. These delays may cause a sudden engine blocktemperature peak which, in turn, may cause the coolant temperature andengine oil temperature to temporarily reach levels which exceed theideal range.

However, if the vehicle is equipped with a novel EETC valve andrestrictor/shutoff valves controlled by the programmed curve, all of theTCF will immediately flow through the radiator upon engine start-up.Accordingly, the likelihood of a sudden engine block temperature peakwill be reduced. This is because the curves shown in FIGS. 19, 20, 22A,22B, 24 and 26 indicate that at an ambient temperature of 100 degreesFahrenheit and a TCF temperature above 100 degrees Fahrenheit, the EETCvalve should be in the open state and the restrictor/shutoff valveshould be in the unblocked/unrestricted state. Of course, there will bea two or three second delay before the valves can be placed in thesestates after starting the engine to allow the hydraulic fluid system toreach proper operating pressure. This anticipatory feature is aninherent benefit of controlling the state of a flow control valvesaccording to a programmed curve.

As discussed above, in one embodiment of the invention, the ECU receivessignals indicative of the ambient air temperature, the engine oiltemperature, and the temperature control fluid temperature. The ECUcompares these signals to one or more temperature control curves. In thepreferred embodiment, the ECU compares the engine oil temperature to anoptimum engine oil temperature curve. The ECU determines the operatingstate of the engine based on this comparison (e.g., normal, high orextremely high load). The ECU then compares the actual temperatures ofthe ambient air and the temperature control fluid to a curve or set ofpredetermined values for determining the desired state or position ofthe flow control valves (e.g., EETC valve, restrictor valves). The setof predetermined values preferably defines a curve which is a functionof at least ambient air temperature and temperature control fluidtemperature. A portion of the preferred curve has a non-zero slope. TheECU sends control signals to the solenoids to open and close thehydraulic fluid injectors. This, in turn, causes the opening and closingof the flow control valves as required.

In an alternate embodiment of the invention, the ECU compares the actualoil temperature against an optimum engine oil temperature value orseries of values defining a curve. If the actual oil temperature isabove the optimum or desired engine oil temperature value, then the ECUadjusts the Normal temperature control curve instead of switching to aHigh Load curve. Specifically, the ECU shifts the Normal temperaturecurve downward a predetermined amount so as to reduce the temperature ofthe temperature control fluid which causes actuation of the valvesbetween their states or positions. In one embodiment of the invention,for every one degree Fahrenheit that the actual engine oil temperatureis above the optimum engine oil temperature there is a corresponding twodegree Fahrenheit decrease in the temperature control fluid temperaturecomponent which produces actuation of the valves. This effectivelyresults in a downward shifting of the temperature control curve.Different engine configurations will, of course, result in differentamounts that the temperature control fluid temperature component isshifted downward for a one degree rise in actual engine oil temperature.For example, a one degree rise in actual oil temperature above theoptimum oil temperature value may produce a decrease in the actuationtemperature of the temperature control fluid within a range of betweenabout one and ten degrees. Furthermore, it is contemplated that theamount of downward shifting of the temperature component may not beconstant (e.g., the amount of downward shifting may increase as thedifference between the actual oil temperature and the optimum oiltemperature increases).

In yet another embodiment, the amount of downward shifting of thetemperature control fluid temperature component may also vary withchanges in ambient temperature. For example, at 0 degrees ambient airtemperature, every one degree that the actual oil temperature is abovethe optimum oil temperature produces a one degree decrease in thetemperature control fluid temperature component. At 50 degrees ambientair temperature, every one degree that the actual oil temperature isabove the optimum oil temperature produces a two degree decrease in thetemperature control fluid temperature component. At 80 degrees ambientair temperature, every one degree that the actual oil temperature isabove the optimum oil temperature produces a three degree decrease inthe temperature control fluid temperature component. This embodiment ofthe invention may be graphically illustrated as shown in FIG. 45Awherein a control curve is selected by the ECU depending on the sensedambient temperature. A plurality of control curves could be plottedrepresenting a range of ambient temperatures. For example, controlcurves could be plotted from about -60 degrees Fahrenheit to about 110degrees Fahrenheit, each having an associated adjustment factor foradjusting the temperature control fluid temperature component and/or forshifting the set of predetermined values. The adjustment factors mayvary. The ECU may also be configured to interpolate between designatedcurves of providing an accurate adjustment factor. Although linearcurves are illustrated in the exemplary embodiment, it should beunderstood that alternate non-linear curves may be incorporated for eachambient temperature. It is also contemplated that a single curve may beutilized for shifting the temperature control curve. One axis of theplot would represent the sensed ambient temperature. The second axiswould represent the ratio of a one degree increase in engine oil overthe corresponding downward shifting of the temperature control curve(e.g., 1/1, 1/2 or 1/3).

Alternately, it may be preferable to wait until the actual oiltemperature exceeds the optimum oil temperature value by a set amountbefore altering the temperature control curve. For example, for every 3or 5 degree increase in the actual engine oil temperature above theoptimum oil temperature value there is a corresponding decrease in theset point temperature of the temperature control fluid which directsactuation of the valve. FIG. 45B graphically illustrates this aspect ofthe invention. A series of identical temperature control curves areshown for a plurality of actual sensed engine oil temperatures. Eachdashed line (NC') represents a shifted-down version of the solid"normal" temperature control curve (NC). It should be readily apparentthat only one particular curve or value would be utilized for a givensensed engine oil temperature. In an alternate arrangement, an equationand/or scaling factor instead of a separate curve may be utilized toalter the value at which actuation occurs according to the normal curve.

In many instances, altering the temperature control fluid componentbased only on the amount that the actual engine oil temperature exceedsthe optimum engine oil value would be sufficient. However, in thepreferred embodiment, it is also desirable to monitor the engine load todetermine how much altering of the temperature control curves isrequired to maintain the actual engine oil temperature at or near theoptimum oil temperature.

One method for varying or altering the temperature control curve as afunction of engine load is by monitoring the rate of change of theactual engine oil temperature. Referring to FIG. 45C, an exemplary curveis illustrated which depicts the rate of change of the actual engine oiltemperature versus the scaling or adjustment factor for the temperaturecontrol fluid temperature component and/or for determining the downwardshifting of the set of predetermined values. If the detected rate ofchange of the actual oil temperature is relatively low (R₁), thedownward shifting of the temperature control curves is also small (S₁).If, on the other hand, the detected rate of change of actual oiltemperature is large (R₂) which is indicative of a high loadingcondition, then the downward shifting of the temperature control curveis also relatively large (S₂). Although the exemplary curve depicts alinear curve other curve shapes, such as exponential, logarithmic,curvilinear, etc., may be substituted therefor. Furthermore, a stepfunction may instead be utilized which provides a different amount ofdownward shifting of the temperature control curve for differentdetected rates of change of the actual engine oil.

During use, when the engine computer detects that the actual sensed oiltemperature exceeds the optimum oil temperature, the computer thendetermines rate of change of the actual engine oil temperature. Theengine computer determines a scaling or adjustment factor from this rateof change. The adjustment factor is then applied to the normaltemperature curve to shift the curve downward. The engine computercontinues to monitor the rate of change in the actual oil temperatureand shifts the temperature control curve accordingly. Delays can beincorporated into the system to minimize the amount of shifting of thetemperature control curve that occurs.

An analytically determined curve illustrating the effect of the aboveembodiment is shown in FIG. 46. The curve shown is for a constantambient temperature of 60° F. From time t₀ to time t₁, the enginecomputer controls the opening and closing of the EETC valve andrestrictor valves according to a normal temperature control curve (level1). At time t₁, the engine computer detects an increase in the actualoil temperature above the optimum engine oil temperature value(approximately 235° F. in the illustrated embodiment) which ispreferably determined from an optimum engine oil temperature curvesimilar to the one shown in FIG. 25. The engine computer either appliesa predetermined factor for downward shifting of the temperature controlcurve (e.g., 2 degree drop in TCF for each 1 degree rise in engine oiltemperature) or, more preferably, the engine computer determines a rateof change of the engine oil temperature and from that rate calculatesthe amount of downward shifting of the temperature control curverequired.

The EETC valve is opened according to the new shifted temperaturecontrol curve (level 2), causing the immediate drop in the temperaturecontrol fluid as shown between time t₁ and t₂. The engine oil however,will continue to rise until the cooling effect of the temperaturecontrol fluid begins to cool the engine oil.

The engine computer continues to monitor the actual engine oiltemperature. At time t₂, the temperature of the temperature controlfluid stabilizes at the new shifted temperature control fluid valve. Ifthe actual engine oil is still above the optimum engine oil temperature,the engine computer determines the rate of change of engine oiltemperature between time t₁ and t₂. The high rate of change indicates acontinued high engine load condition. Accordingly, based on thisdetermined rate, the engine computer determines an additional amount ofdownward shifting of the temperature control curve that is required. Theflow control valve or valves are then controlled based on the thissecond shifted temperature control curve (level 3).

At time t₃ the engine computer determines a rate of change of the engineoil temperature between time t₂ and t₃. Since the new rate of change inthe illustrated example is less than the previous rate of change, theengine computer does not shift the temperature control curve downward.Instead, the engine computer continues to control the flow control valveor valves based on the level 3 temperature control curve.

At time t₅ the engine computer determines a rate of change of the engineoil temperature between time t₄ and t₅. Since the new rate of change inthe illustrated example is decreasing, the engine computer shifts thetemperature control curve upward back toward the first or normal level.As a result, the temperature control fluid temperature continues to heatup while the engine oil decreases in temperature and begins to return toits optimal operating temperature.

Since the reheating of the temperature control fluid is a slow process,as illustrated by the time period between time t₅ and t₆, it isimportant not to drop the temperature control fluid to an unnecessarilylow temperature so as to maintain the engine oil as close to the optimumengine oil as possible.

It should be understood that the sensed ambient air temperature willaffect rate or slope of the temperature control fluid temperature curvein FIG. 46. For example, at hot ambient temperatures, the temperatureslope of the temperature control fluid between time t₅ and t₆ will besteeper than at low ambient temperatures. This is due to the fact thatat lower temperatures (e.g., zero degrees ambient) it is more preferablethat the engine oil remains at a higher temperature for a longer periodof time to increase heater and defroster capabilities. The cold ambienttemperature reduces the likelihood that the engine oil will becomeexcessively hot. In warmer ambient temperatures, it is desirable tomaintain the engine oil closer to its optimum valve so as to preventoverheating. The temperature slope of the temperature control fluid is,thus, steeper at these warmer temperatures.

An alternate method for determining the engine load is by monitoring theintake manifold vacuum pressure. The sensed intake manifold pressuregenerally provides an accurate indication of the current engine load.For example, if the sensed intake manifold vacuum pressure is less thanabout 4 inches Hg, the engine is operating under a high load condition.Accordingly, a first predetermined adjustment factor or curve can beselected for reducing or replacing the temperature control curve. If,however, the intake manifold vacuum pressure is less than about 2 inchesHg, then the engine is operating under an extremely load condition. Inthis case, a second adjustment factor is selected for varying the normaltemperature control curve.

Yet another method for determining engine load is through the monitoringof the commanded engine acceleration. For example, a high commandedengine acceleration is indicative of a high engine load condition. Theamount of engine acceleration can be determined from a variety ofmethods, such as the accelerator pedal displacement, a signal from thefuel injection system, etc. Depending on the commanded acceleration, apredetermined factor and/or curve is selected for varying the normaltemperature control curve.

In both the commanded engine acceleration method and the intake manifoldvacuum pressure method, a rate monitoring system similar to the onediscussed above with respect to the engine oil temperature could also beincorporated to further optimize these methods.

FIG. 47 is an actual plot of the present invention incorporated into aGM 3800 V6 engine. The data was recorded as the vehicle was being drivenup a very steep incline. The data which is shown is the engine oiltemperature (curve A), the temperature of the temperature control fluid(curve B), the temperature of ambient air (curve C), the speed of thevehicle (curve D) and the vacuum pressure (curve E). The X axisrepresents a time period of several minutes. At point Z₁, anacceleration was commanded by the vehicle, increasing its speed fromapproximately 55 miles per hour to over 90 miles per hour. The increasein engine speed and acceleration results in a corresponding decrease invacuum pressure and an increase in the temperature of the engine oil.The temperature control system detects the increase in engine oiltemperature and, accordingly, reduces the temperature of the temperaturecontrol fluid. At point Z₂, the lower temperature of the temperaturecontrol fluid begins to reduce the temperature of the engine oil. FIG.47 clearly illustrates the interrelationship between detected engineload conditions (acceleration, velocity, and/or vacuum pressure) and theengine oil and temperature control fluid temperatures.

Based on the above discussion, those skilled in the art would readilyunderstand and appreciate that various modifications can be made to theexemplary embodiments disclosed and are well within the scope of thisinvention. For example, the temperature control curves themselves may bereplaced by one or more equations for controlling the actuation of thevalves. In yet another embodiment, fuzzy logic controllers could beimplemented for controlling the actuation of the valves and/or varyingof the temperature control curves.

The varying or downward shifting of the temperature control curves asdiscussed above is preferably limited to between approximately 50°F.-70° F. This is intended to prevent substantial degradation in thecapabilities of the heater/defroster systems by maintaining thetemperature control fluid at a reasonably high temperature.

The above methods for adjusting the temperature control curves can alsobe utilized in the star up/warm up phase. For example, if the actualengine oil temperature is below the desired or optimum engine oiltemperature by a predetermined amount, an adjustment factor can beapplied to the temperature control curve to shift it upward a presetamount. Preferably, the amount of adjustment would also vary with theambient air temperature such that the shifted temperature control curvewould be similar to the start-up/warm-up curve shown in FIG. 26.

The above discussion has been directed toward a temperature controlsystem which controls engine oil temperature so as to maintain it at ornear its optimum temperature. However, it is contemplated that, incertain cases, optimal control may not be necessary. In light of this,another embodiment of the present invention is disclosed which does notutilize curves that vary with ambient temperature for controllingactuation of the valves. Instead, one or more predetermined engine oiland/or temperature control fluid temperature values are utilized forcontrolling the valves regardless of ambient air temperature. Thepredetermined engine oil and temperature control fluid temperatures arepreferably chosen so as to provide an acceptable temperature state forthe engine over a wide range of ambient temperatures. For example, anaverage engine oil temperature value of approximately 260° F. may beutilized as the predetermined value.

Referring to FIG. 48, a graphical illustration of this embodiment of theinvention is shown. In this embodiment, the temperature control systemis operated so as to maintain the engine oil at or near at least oneengine oil temperature value (designated by the letter `A`). Theoperation of the system is as follows. A sensor within the enginedetects a temperature indicative of the temperature of the engine oil.This may be accomplished, for example, by directly sensing thetemperature of the oil within the oil pan, or by sensing the temperatureof the engine block or the oil pan itself. Hence, any temperature whichgenerally represents the temperature of the engine oil (or is a functionof that temperature) can be sensed and utilized in the presentinvention. This signal is sent to the engine computer. The enginecomputer compares the signal to a predetermined engine oil temperaturevalue. If the sensed oil temperature signal is less than thepredetermined engine oil temperature value, the engine oil is in arelatively cold state. In this state, it is not desirable to circulate aflow of temperature control fluid. The engine computer may be utilizedto determine the position of the valve controlling the flow oftemperature control fluid between the radiator and the engine (e.g.,EETC valve). The engine computer can determine the position of the valvemany different ways. One way involves providing signals from the valvewhich indicate its position. If the valve is in its open position(allowing flow of temperature control fluid between the radiator and theengine) then it is desirable for engine computer to send signals tocause the valve to close (inhibiting flow of temperature control fluidfrom the radiator).

In the above discussion, the engine computer determines the position ofthe valve and automatically closes the valve based on only thetemperature of the engine oil. However, it is contemplated that theengine computer may also utilize the temperature of the temperaturecontrol fluid for controlling the opening and closing of the valve. Byutilizing the temperature of the temperature control fluid the systemcan more readily account for the lag time involved in heating the oil(i.e., engine heats up quicker than engine oil) In this embodiment, asignal indicative of the actual or sensed temperature of the temperaturecontrol fluid is sent to the engine computer. The engine computercompares this signal (or temperature) against at least one predeterminedtemperature control fluid temperature value. If the actual sensedtemperature is below the predetermined temperature control fluidtemperature value then the valve is likely in its closed positioninhibiting flow between the radiator and the engine. By leaving thevalve is its closed position, the temperature of the engine oil willrise since there is no cooling being provided by fluid from theradiator.

If, on the other hand, the sensed temperature of the temperature controlfluid is greater than the predetermined temperature control fluidtemperature value, then the valve be in its open position allowingtemperature control fluid to circulate from the radiator into theengine. However, since the temperature of the engine oil is relativelycold, it is desirable that the valve be placed in its closed position.In order to close the valve (if it is not already in its closedposition), the engine computer shifts the predetermined temperaturecontrol fluid temperature value upward a prescribed amount. This isequivalent to adjusting or increasing the predetermined temperaturevalue. The amount of shifting or adjusting may depend on variousfactors. Preferably, the amount of upward shifting is a function of theamount that the actual engine oil temperature is below the predeterminedengine oil temperature value. A detailed discussion has already beenprovided hereinabove on shifting or adjusting predetermined temperaturevalues or components.

It may instead be desirable to adjust or increase the predeterminedtemperature control fluid temperature value an amount that willautomatically place it above the actual temperature control fluidtemperature, regardless of the comparison of the actual engine oiltemperature to the predetermined engine oil temperature value. Theengine computer would then maintain the predetermined temperaturecontrol fluid value at that temperature (or above) until the actualengine oil temperature reaches the predetermined engine oil temperaturevalue. In another embodiment, the engine computer does not adjust thepredetermined temperature control fluid temperature value but simplymaintains the valve in the closed position until the actual engine oiltemperature reaches the predetermined engine oil temperature value.

When the engine computer receives an engine oil temperature signal whichis above the predetermined engine oil temperature value, then engine isin a relatively hot state. In this state it is desirable to circulatecool temperature control fluid from the radiator through the waterjackets surrounding the engine. As discussed above, the engine computermay be utilized to determine the position of the valve and thenautomatically place the valve in a desired position (e.g., open).However, in one preferred embodiment, the engine computer also utilizesthe actual or sensed temperature of the temperature control fluid. Theengine computer compares the temperature of the temperature controlfluid to at least one predetermined temperature control fluidtemperature value. If the actual sensed temperature is above thepredetermined temperature control fluid temperature value, then thevalve should already be in its open position allowing temperaturecontrol fluid flow between the radiator and the engine. However, if thesensed temperature of the temperature control fluid is less than thepredetermined temperature control fluid temperature value, then thevalve is likely to be in its closed position. It is therefore desirableto open the valve so as to cool the engine. In order to do so, theengine computer shifts or adjusts the predetermined temperature controlfluid temperature value downward a prescribed amount in a similar manneras described above. When the actual temperature of the temperaturecontrol fluid exceeds the shifted or adjusted predetermined temperaturecontrol value, the valve will open.

FIG. 48 also illustrates upper and lower temperature control fluidtemperature limits (letters `C` and `D`). These temperature limitsprevent the temperature control system from significantly reducing theeffectiveness of the heater/defrost system.

The preferred temperature control system utilizes the engine computer tocontinuously shift or adjust the predetermined temperature controltemperature value based on the comparison of the actual engine oiltemperature value to the predetermined engine oil temperature value.Thus, the shifted or adjusted predetermined temperature control valuemay not necessarily cause immediate actuation of the valve. Instead, thenew shifted value may simply be closer, temperature-wise, to the actualtemperature resulting in quicker actuation of the valve. In analternate, but not preferred embodiment, the predetermined temperaturecontrol fluid temperature value is not adjusted. Instead, the sensed oractual temperature control fluid temperature is adjusted and thencompared against the predetermined temperature control fluid temperaturevalue. Those skilled in the art would readily be capable of practicingalternate methods for controlling the temperature control system basedon the engine oil temperature. These alternate methods are well withinthe purview of the claims.

In operation, the above system functions as follows. During initialstart-up, if the engine computer senses that the engine oil temperatureis less than approximately 230° F., the engine computer raises or setsthe predetermined temperature control fluid temperature value toapproximately 240° F. until the engine computer detects that the engineoil temperature is at or near approximately 230° F. which is its normaloperating temperature.

If the engine computer subsequently determines that the engine oiltemperature is greater than approximately 230° F., the computer shiftsthe predetermined temperature control fluid temperature value from itsnormal operational value (e.g., approximately 200° F.) to a lower value.The shifting is achieved by decreasing the predetermined temperaturecontrol fluid temperature value 2° F. for every 1° F. that the actualengine oil temperature exceeds the predetermined engine oil temperaturevalue. The downward shifting of the predetermined temperature controlfluid temperature value is limited to approximately 170° F.

If after reaching the normal engine oil operating temperature, theengine computer subsequently determines that the engine oil temperatureis less than approximately 230° F., the computer shifts thepredetermined temperature control fluid temperature value from itsnormal operational value (e.g., approximately 200° F.) to a highervalue. The shifting is achieved by increasing the predeterminedtemperature control fluid temperature value 2° F. for every 1° F. thatthe actual engine oil temperature is below the predetermined engine oiltemperature. The upward shifting of the predetermined temperaturecontrol fluid temperature value is limited to approximately 240° F.

It is also contemplated that the control logic for the temperaturecontrol system may be incorporated into computer chips or processorsmounted directly in the valve instead of in the engine computer. Hence,while the above discussion has concentrated on utilizing an enginecomputer for controlling the valves, it is also contemplated that otherelectronic control mechanisms may be utilized in its stead.

Although the EETC valves disclose fluid injectors which are integratedinto the valve housing, the scope of the invention includes anembodiment wherein the fluid injectors are physically separated from thereciprocating EETC valve components and connected by fluid linestherebetween. Likewise, the fluid injectors associated with therestrictor/shutoff valves can be either integrated into the valvehousing as shown in FIG. 38, or can be physically separated from thereciprocating valve components as shown in FIGS. 33 and 34.Alternatively, fluid injectors associated with an integrated valve suchas shown in FIG. 38 can control the state of other restrictor/shutoffvalves which do not have their own fluid injectors.

While the preferred embodiment utilizes an ECU to provide pressurizedhydraulic oil to the EETC valve for actuating the valve member 146, asimpler and less precise means for providing the pressurized fluid is bymounting a thermostat-type device within the hydraulic fluid linesleading to and from the EETC. The thermostat would provide pressurizedhydraulic fluid when the oil in the line or in the pan exceeds aprescribed temperature which, in the preferred embodiment, is chosen tobe indicative of the engine oil temperature. A drawback to this type ofa system is that a mechanism must be added to the system which removesor release the oil in the EETC valve when it is desired to close thevalve, i.e., depressurize the diaphragm.

As stated above, the preferred valve in the present invention isoperated through the use of hydraulic fluid. However, other types ofvalves may also be utilized within the scope of this invention. Forexample, referring to FIG. 49, an electronically assisted thermostat 950is illustrated which can be utilized in one embodiment of the presentinvention. The electronically assisted thermostat 950, to an extent, isconfigured and operates similar to a conventional thermostat. Theconventional portion of the electronically assisted thermostat 950includes an outer housing 952, a valve member 954, a wax pellet 956, anda return spring 958. The wax pellet 956 is designed to maintain thevalve member 954 in a closed position when the wax pellet 956 issolidified. The return spring 958 is configured to bias the valve member954 into an open position when the wax pellet 956 is melted. The detailsof the configuration and operation of conventional thermostats is wellknown to those skilled in the art.

The electronically assisted thermostat 950 also includes a heatingelement 960, such as a coil, which extends around or through the waxpellet 956. The heating element 960 is electrically connected to a powersource (not shown) through an electrical cable 962. A computer, such asthe ECU 900, controls the transmission of electric current along thecable 962 to the heating element 960. The heating element 960 isdesigned to heat up to an elevated temperature when current is suppliedto it. The heat from the heating element 960 exposes the wax pellet 956to an approximately 80 degree Fahrenheit temperature increase. Thisassists in melting the wax pellet 956 sooner than it would otherwisemelt. Heating elements, such as dielectric heaters and resistanceheaters, are well known in the art and, thus, no further details arerequired.

In order to operate more efficiently in the present system, the waxpellet 956 is calibrated to begin to open between 220° F. and 226° F.and to be fully open at a fluid temperature between 236° F. and 240° F.These temperatures are higher than current thermostat designs (e.g.,approximately 180° F.). However, maintaining the temperature controlsystem as a closed circuit (i.e., no radiator) until the temperaturecontrol fluid reaches 220° F. produces increased pressure (approximately7 psi) in the system. To accommodate this increased pressure, the waxpellet 956 is preferably manufactured slightly larger then conventionalpellets. A larger return spring 958 and housing 952 may also benecessary.

The ability of the heating element 960 to melt the wax pellet 956 80° F.before it would normally melt permits control over the temperaturecontrol fluid flow for a variety of temperature control fluidtemperatures. The 80° F. temperature limit on the heating element 960provides the lower limit at which the valve member 954 can be opened(e.g., lower temperature limit of 160° F.). This helps prevent loss ofthe heater and defrost capabilities of the system. The upper temperaturelimit is maintained at 240° F. by the melt temperature of the wax pellet956 itself.

The operation of one preferred embodiment of the electronically assistedthermostat 950 will now be discussed. The ECU 900 receives a signalindicative of the actual engine oil or block temperature. If actualengine temperature is less than a predetermined engine temperature value(e.g., the desired engine oil temperature value for a given sensedambient air temperature), the thermostat operates in a conventionalmanner (e.g., initial opening when the temperature control fluid reaches220° F./226° F.). If, however, the actual engine temperature is greaterthan the predetermined engine temperature value, the ECU 900 controlsthe transmission of current along the cable 962. The current results inheating of the heating element 960 which, in turn, causes the wax pellet956 to begin to melt, thereby initiating opening of the thermostat.

The electronically assisted thermostat 950 described above provides asimple, lightweight device for efficiently controlling the flow oftemperature control fluid.

The inlet hydraulic fluid injector employed in the novel EETC andrestrictor/shutoff valves must tap into a source of pressurizedhydraulic fluid to fill the respective valve chambers. Typical valveswill tap into that source for about six seconds to fully change state. Aslightly longer time period may be required for systems where a singleinjector fills the chambers of multiple restrictor/shutoff valves. Thesetime periods are very short compared to the average length of a vehicletrip. Since valve states are unlikely to be changed more than a fewtimes during a normal vehicle trip, the percentage of time that thepressurized source is tapped is anticipated to be very small, typicallyunder one minute for every hour of driving, or less than 2%.Accordingly, there should be little, if any, effect on the normalfunctioning of the hydraulic fluid system. Thus, if the enginelubrication oil pump outlet lines are the source of the hydraulic fluid,the operation of the novel valves should not have any significant effecton the normal operation of the lubrication system. Nor should it benecessary to modify existing oil pumps or lubrication systems toaccommodate the novel valves. The lines may tap off of the cylinder heador the block itself if desired, thus, requiring very little change tothe existing engine envelope.

The preferred novel EETC and restrictor/shutoff valves described abovereciprocate between a first position for allowing unrestricted flow offluid through at least one passageway and a second position forrestricting the flow through the passageway. The flow restriction iseither partial or complete (i.e., 100 percent). Each of the valves arebiased in one of the positions by a biasing spring and placed in theother position by hydraulic fluid pressure pushing against a pistonmember. In the EETC valves, the piston member is, preferably, either adiaphragm or a piston shaft. In the restrictor/shutoff valve, the pistonmember comprises a combination of a separate piston and shaft.

Although the EETC and restrictor/shutoff valves are shown as having afirst position associated with a pressurized, fully filled chamber and asecond position associated with an unpressurized, empty chamber, each ofthe valves can be designed to operate in reverse. That is, the positionof the chambers and biasing springs can be reversed so that the valve isin a first position when the chamber is unpressurized and empty and isin a second position when the chamber is pressurized and fully filled.The scope of the invention includes such reversed configurations.

Likewise, the scope of the invention includes embodiments wherein theEETC and restrictor/shutoff valves are placed in positions between thefirst and second positions by only partially filling and pressurizingthe respective chambers. To achieve a desired mid-position for aparticular valve, chamber pressure values and/or filling or emptyingtime periods must be empirically determined for that valve. For example,if a particular EETC valve is fully opened by pressurizing the chamberto 25 psi and continuing to pressurize for two seconds after the chamberreaches 25 psi, a procedure of pressurizing until the chamber reaches 15psi might place the valve in the desired mid-position. Alternatively, ifit is desired to move an open EETC valve to a mid-position, partialchamber depressurization could be employed. Again, the particularpressure values and additional time periods must be empiricallydetermined for a given novel valve. Once those values are determined,the ECU can be pre-programmed with the values to achieve the desiredmid-position(s). Alternatively, a feedback control system employingvalve position transducers connected to the ECU could be employed.

While the temperature control system of the present invention has beendescribed as replacing the thermostat of an internal combustion engine,the system can also be utilized in conjunction with the a standardthermostat. An embodiment of this type would, preferably, incorporate aEETC valve in series with the thermostat. That is, the fluid line to theradiator would have both a standard thermostat mounted thereon, as wellas an EETC valve. An ECU would determine when the EETC valve will havecontrol over the fluid flow. Preferably, the EETC valve would controlthe initial start-up/warm-up mode of the engine, which is when thethermostat does not operate efficiently. In this mode, a means forinhibiting the thermostat would have to be incorporated to prevent thethermostat from opening the line to the radiator before the engineapproaches its optimum temperature. For example, a pin could be actuatedto lock the valve of the thermostat in the closed position. Theactuation of the pin would be controlled by the ECU based on one of thevalve control graphs discussed above. Accordingly, the EETC valve wouldbe in control of the system until the TCF fluid reaches its normaloperating temperature whereupon the EETC valve would be inhibited fromfurther control and the thermostat would be released to control thesystem as is commonly performed. The thermostat could also be locked outwhen the ambient temperature falls below a predetermined temperature,such as zero degrees Fahrenheit.

It is envisioned that this embodiment would be utilized in situationswhere retrofitting of an existing engine is more desirable then fullyimplementing the disclosed temperature control system. Since thetemperature control system disclosed provides significant benefitsduring start-up/warm-up and at low temperatures, the modified embodimentdiscussed above has advantages over a standard thermostatic system.

Another feature of the present invention is the ability to controlvarious other engine parameters in combination with the control of theTCF. For example, it is possible to control the electric fan whichprovides cooling for the radiator. When the temperature of the TCFmeasured at the outlet of the radiator is approximately between about150 degrees and 160 degrees Fahrenheit, and the vehicle speed is lessthan about 35 miles per hour, the fan is designed be operative. Thiscorresponds to the operational state wherein the car is movingrelatively slowly and the TCF is being to become hot car. It istypically in this operational state where most overheating will occur.When the car is traveling above 35 miles per hour, the air flowingthrough the radiator and around the engine block will function to reducethe TCF temperature. Variations on the control of the fan are alsopossible. The ECU can be programmed to provide the fan control or,instead, a separate fan control unit may be utilized.

It is also possible to control the spark generated by the spark plugutilizing signals from the ECU. For example, the temperature of the TCFin the radiator and the ambient air temperature can be monitored todetermine how much spark is required to produce the optimum combustionof the fuel. It is preferable to utilize the TCF temperature in theradiator since this valve should be relatively stable as compared withthe TCF temperature out of the engine block which may varysignificantly. Those skilled in the art would readily understand thatother modifications can be made to the operational state of the internalcombustion engine when utilizing the novel system disclosed.

The temperature control system of the present invention providesadditional consequential benefits. By providing the means to increasethe actual temperature of the TCF fluid in cold temperature environments(see FIG. 23), the physical size of the heater can be decreased. This isbecause the hotter the temperature of the TCF, the less heater coresurface area required to extract the necessary amounts of heat energyfrom the TCF to warm the vehicle's passenger compartment.

An engine employing the EETC valve and one or more restrictor/shutoffvalves will have less engine out exhaust emissions and greater fueleconomy than a prior art engine cooling system employing only a priorart thermostat. Since the reduction in emissions and improvement in fueleconomy will be greatest in cold temperature environments and duringengine start-up, the invention offers the possibility to significantlyreduce vehicle exhaust pollution levels. An engine incorporating thenovel EETC and restrictor valves should also produce increasedhorsepower at lower temperatures.

Currently, the United States Environmental Protection Agency conductsits emissions testing in relatively warm ambient air temperatures.Testing in these warm temperatures does not expose the actual pollutingeffects of vehicles when they are started and operated in coldtemperature climates. For example, the current testing procedurerequires that a vehicle "cold soak" in an ambient air temperature of 68to 80 degrees Fahrenheit for 12 hours. That is, the vehicle must situnused for 12 hours in this temperature environment so that the engineparts stabilize to that ambient air temperature. Then, the engine isstarted and emissions are measured to verify that they are withinacceptable limits. Since the ambient air temperature is relatively warmthe engine and catalytic converter quickly heat up to an efficientoperating temperature. Most vehicles today would fail the currentemissions standards if the "cold soak" test was required to be performedin significantly lower ambient air temperatures, such as 28 to 40degrees Fahrenheit. An engine employing the EETC valve along withrestrictor/shutoff valves or the engine block by-pass system illustratedin FIGS. 44A and 44B, will show a substantial improvement over currentsystems towards meeting current emissions standards under a "cold soak"test at such lower ambient air temperatures.

The inventions disclosed above provide an effective way to harness theunderestimated one-third of heat energy handled by a vehicle's coolingsystem (see the excerpt in the Background of the Invention from page 111of the Goodheart-Willcox automotive encyclopedia). The EETC valve, therestrictor/shutoff valve, and the use of programmed curves fordetermining their states are the basic building blocks for an enginetemperature control system that effectively tailors the performance ofthe engine cooling system with the overall needs of the vehicle.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification, as indicating the scope of theinvention.

I claim:
 1. A temperature control system in a liquid cooled internalcombustion engine equipped with a radiator and an engine, the systemcomprising:a flow control valve for controlling flow of a temperaturecontrol fluid between the engine and the radiator, the flow controlvalve having a first state for inhibiting said flow and a second statefor allowing said flow; a first sensor for sensing a temperatureindicative of engine oil temperature and for providing an engine oiltemperature signal; and a second sensor for sensing a temperaturecontrol fluid temperature and for providing a temperature control fluidtemperature signal; and an engine computer for receiving the engine oiltemperature signal and the temperature control fluid temperature signal,the engine computer comparing the engine oil temperature signal to apredetermined engine oil temperature value to determine the temperaturestate of the engine, the engine computer determining a temperaturecontrol fluid temperature value for controlling the valve state, thetemperature control fluid temperature value being a function of thecomparison of the engine oil temperature to the predetermined engine oiltemperature, the engine computer comparing the temperature control fluidtemperature signal to the temperature control fluid temperature value todetermine a desired valve state, the engine computer providing signalsfor controlling the actuation of the flow control valve between itsfirst and second states as a function of the comparisons.
 2. Atemperature control system according to claim 1 wherein the enginecomputer controls the flow control valve so that the valve is in itsfirst state when the engine oil temperature signal is less than thepredetermined engine oil temperature value and in its second state whenthe engine oil temperature signal is greater than the predeterminedengine oil temperature value and the temperature control fluidtemperature signal is greater than the temperature control fluidtemperature value.
 3. A temperature control system according to claim 1wherein the temperature sensed by the sensor is the temperature of theengine block.
 4. A temperature control system according to claim 1wherein the flow control valve is an electronically assisted thermostat.5. A temperature control system in a liquid cooled internal combustionengine equipped with a radiator and an engine, the system comprising:aflow control valve for controlling flow of a temperature control fluidbetween the engine and the radiator, the flow control valve having afirst state for inhibiting said flow and a second state for allowingsaid flow, the flow control valve being an electronically assistedthermostat; a first sensor for sensing a temperature indicative ofengine oil temperature and for providing an engine oil temperaturesignal; and a second sensor for sensing a temperature control fluidtemperature and for providing a temperature control fluid temperaturesignal; an engine computer for receiving the engine oil temperaturesignal and the temperature control fluid temperature signal, the enginecomputer comparing the engine oil temperature signal to a predeterminedengine oil temperature value to determine the temperature state of theengine, the engine computer comparing the temperature control fluidtemperature signal to a temperature control fluid temperature value ifthe engine oil temperature signal exceeds the predetermined engine oiltemperature value, the engine computer providing signals for controllingthe actuation of the flow control valve between its first and secondstates as a function of the comparisons; wherein the electronicallyassisted thermostat includesa housing; a valve member reciprocatablewithin the housing between the open state and the closed state; a returnspring for biasing the valve member into the open state; a wax pelletattached to the valve member and having a solid state and a liquidstate, the wax pellet maintaining the valve member in its closed statewhen the wax pellet is in its solid state, and the wax pellet allowingthe return spring to bias the valve member into its open position whenthe wax pellet is in its liquid state; a heating element mounted withinthe housing and adapted to transfer heat to wax pellet, the heatingelement receiving an electrical transmission for producing heating ofthe heating element; and wherein the signals from the engine computercontrol the electrical transmission to the heating element.
 6. Atemperature control system according to claim 5 wherein the heatingelement is a heating coil looped around the wax pellet.
 7. A temperaturecontrol system according to claim 5 wherein the heating element isdisposed within the wax pellet.
 8. A temperature control systemaccording to claim 5 wherein the wax pellet has a melting point ofapproximately 220° F.
 9. A temperature control system according to claim5 wherein the engine computer controls the electrical transmission so asto produce heating of the heating element when the engine oiltemperature signal is greater than the predetermined engine oiltemperature value.
 10. A temperature control system in a liquid cooledinternal combustion engine comprising:a flow control valve forcontrolling flow of a temperature control fluid, the flow control valvehaving a first state for inhibiting said flow and a second state forallowing said flow; a first sensor for sensing a temperature indicativeof engine oil temperature and for providing a signal indicative thereof;a second sensor for sensing a temperature indicative of the temperaturecontrol fluid temperature and for providing a signal indicative thereof;and an engine computer for receiving the engine oil temperature signaland the temperature control fluid temperature signal, the enginecomputer comparing the engine oil temperature signal to a predeterminedengine oil temperature value, the engine computer adjusting apredetermined temperature control fluid temperature value based on thecomparison of the engine oil temperature signal to a predeterminedengine oil temperature value, wherein the engine computer adjusts thepredetermined temperature control fluid temperature value downward ifthe engine oil temperature signal exceeds the predetermined engine oiltemperature value, and wherein the engine computer adjusts thepredetermined temperature control fluid temperature value upward if theengine oil temperature signal is below the predetermined engine oiltemperature value, the engine computer comparing the temperature controlfluid temperature signal to the adjusted predetermined temperaturecontrol fluid value, and the engine computer providing signals forcontrolling the actuation of the flow control valve between its firstand second states as a function of the comparison of the temperaturecontrol fluid temperature signal to the adjusted temperature controlfluid temperature value.
 11. A temperature control system according toclaim 10 wherein the engine computer determines an amount that theengine oil temperature signal exceeds the predetermined engine oiltemperature value and wherein the engine computer adjusts thepredetermined temperature control fluid temperature value as a functionof the amount of said excess.
 12. A temperature control system accordingto claim 10 wherein the engine computer adjusts the predeterminedtemperature control fluid temperature value downward a preset amount foreach one degree that the engine oil temperature signal exceeds thepredetermined engine oil temperature value.
 13. A temperature controlsystem according to claim 12 wherein the preset amount of adjustment isa value within a range of between about one degree Fahrenheit and aboutten degrees Fahrenheit.
 14. A temperature control system according toclaim 10 wherein the flow control valve is an electronically assistedthermostat.
 15. A temperature control system in a liquid cooled internalcombustion engine comprising:a flow control valve for controlling flowof a temperature control fluid, the flow control valve having a firststate for inhibiting said flow and a second state for allowing saidflow, the flow control valve being an electronically assistedthermostat; a first sensor for sensing a temperature indicative ofengine oil temperature and for providing a signal indicative thereof; asecond sensor for sensing a temperature indicative of the temperaturecontrol fluid temperature and for providing a signal indicative thereof;an engine computer for receiving the engine oil temperature signal andthe temperature control fluid temperature signal, the engine computercomparing the engine oil temperature signal to a predetermined engineoil temperature value, the engine computer adjusting a predeterminedtemperature control fluid temperature value based on the comparison ofthe engine oil temperature signal to a predetermined engine oiltemperature value, the engine computer comparing the temperature controlfluid temperature signal to the adjusted predetermined temperaturecontrol fluid value, and the engine computer providing signals forcontrolling the actuation of the flow control valve between its firstand second sates as a function of the comparison of the temperaturecontrol fluid temperature signal to the adjusted temperature controlfluid temperature value wherein the electronically assisted thermostatincludesa housing; a valve member reciprocatable within the housingbetween the open state and the closed state; a return spring for biasingthe valve member into the open state; a wax pellet attached to the valvemember and having a solid state and a liquid state, the wax pelletmaintaining the valve member in its closed state when the wax pellet isin its solid state, and the wax pellet allowing the return spring tobias the valve member into its open position when the wax pellet is inits liquid state; a heating element mounted within the housing andadapted to transfer heat to wax pellet, the heating element receiving anelectrical transmission for producing heating of the heating element;and wherein the signals from the engine computer control the electricaltransmission to the heating element.
 16. A temperature control systemaccording to claim 15 wherein the heating element is a heating coillooped around the wax pellet.
 17. A temperature control system accordingto claim 15 wherein the heating element is disposed within the waxpellet.
 18. A temperature control system according to claim 15 whereinthe wax pellet has a melting point of approximately 220° F.
 19. Atemperature control system according to claim 15 wherein the enginecomputer controls the electrical transmission so as to produce heatingof the heating element when the engine oil temperature signal is greaterthan the predetermined engine oil temperature value.
 20. A temperaturecontrol system in a liquid cooled internal combustion enginecomprising:a flow control valve for controlling flow of a temperaturecontrol fluid, the flow control valve having a first state forinhibiting said flow and a second state for allowing said flow; a firstsensor for sensing a temperature indicative of the temperature of theengine block and for providing a signal indicative thereof; a secondsensor for sensing a temperature indicative of the temperature controlfluid temperature and for providing a signal indicative thereof; and anengine computer for receiving the engine block temperature signal andthe temperature control fluid temperature signal, the engine computercomparing the engine block temperature signal to a predetermined engineblock temperature value, the engine computer adjusting a predeterminedtemperature control fluid temperature value based on the comparison ofthe engine block temperature signal to the predetermined engine blocktemperature value, the engine computer adjusting the predeterminedtemperature control fluid temperature value downward when the endingblock temperature signal is greater than the predetermined enable blocktemperature signal, the ending computer adjusting the predeterminedtemperature control fluid temperature value upward when the engine blocktemperature signal is less than the predetermined engine blocktemperature signal, the engine computer comparing the temperaturecontrol fluid temperature signal to the adjusted predeterminedtemperature control fluid value, and the engine computer providingsignals for controlling the actuation of the flow control valve betweenits first and second states as a function of the comparison of thetemperature control fluid temperature signal to the adjustedpredetermined temperature control fluid temperature value.
 21. A methodfor controlling the state of a flow control valve in an internalcombustion engine, the flow control valve controlling flow oftemperature control fluid through a passageway and having a first statefor inhibiting the flow of temperature control fluid through thepassageway and a second state for allowing the flow of temperaturecontrol fluid through the passageway, the method comprising the stepsof:receiving a temperature signal indicative of the engine oiltemperature; comparing the engine oil temperature signal to apredetermined engine oil temperature value; determining a desired statefor the flow control valve based on the comparison of the engine oiltemperature signal to the predetermined engine oil temperature value,wherein the first state is the desired state of the flow control valvewhen the engine oil temperature signal is below the predetermined engineoil temperature value, and wherein the second state is the desired stateof the flow control valve when the engine oil temperature signal isabove the predetermined engine oil temperature value; and actuating theflow control valve into the desired state.
 22. A method according toclaim 21 further comprising the step of providing signals for actuatingthe flow control valve.
 23. A method for controlling the state of a flowcontrol valve in an internal combustion engine, the flow control valvecontrolling flow of temperature control fluid through a passageway andhaving a first state for inhibiting the flow of temperature controlfluid through the passageway and a second state for allowing the flow oftemperature control fluid through the passageway, the method comprisingthe steps of:receiving a temperature signal indicative of the engine oiltemperature; comparing the engine oil temperature signal to apredetermined engine oil temperature value; and actuating the flowcontrol valve between its first and second states based on thecomparison of the engine oil temperature signal to the predeterminedengine oil temperature value; wherein the flow control valve is anelectronically assisted thermostat and wherein the step of actuating theflow control valve involves sending an electrical transmission to aheating element so as to produce heating of the element, and melting awax pellet by exposing it to the heated coil, the melting of the waxproducing actuation of the valve.
 24. A method for controlling the stateof a flow control valve in an internal combustion engine, the flowcontrol valve controlling flow of temperature control fluid through apassageway and having a first state for inhibiting the flow oftemperature control fluid through the passageway and a second state forallowing the flow of temperature control fluid through the passageway,the method comprising the steps of:receiving an engine oil temperaturesignal indicative of the engine oil temperature; receiving a temperaturecontrol fluid temperature signal indicative of the temperature controlfluid temperature; comparing the engine oil temperature signal to apredetermined engine oil temperature value; adjusting a predeterminedtemperature control fluid temperature value based on the comparison ofthe engine oil temperature signal to the predetermined engine oiltemperature value, wherein the predetermined temperature control fluidtemperature value is adjusted downward when the engine oil temperaturesignal is greater than the predetermined engine oil temperature signal,and wherein the predetermined temperature control fluid temperaturevalue is adjusted upward when the engine oil temperature signal fallsbelow the predetermined engine oil temperature signal; comparing thetemperature control fluid temperature signal to the adjusted temperaturecontrol fluid temperature value; and actuating the flow control valvebetween its first and second states based on the comparison of thetemperature control fluid temperature signal to the adjusted temperaturecontrol fluid temperature value.
 25. A method according to claim 24further comprising the steps of sensing a temperature indicative of theengine oil temperature and providing the engine oil temperature signalindicative thereof, and sensing a temperature control fluid temperatureand providing the temperature control fluid temperature signalindicative thereof.
 26. A method according to claim 24 wherein theadjusting of the temperature control fluid temperature comprises thesteps of:determining the amount that the engine oil temperature signalexceeds the predetermined engine oil temperature value; determining anadjustment factor for adjusting the predetermined temperature controlfluid temperature value based on the amount of said excess; andcombining the adjustment factor and the predetermined temperaturecontrol fluid temperature value to form the adjusted temperature controlfluid temperature value.
 27. A method for controlling the state of aflow control valve in an internal combustion engine, the flow controlvalve controlling flow of temperature control fluid through a passagewayand having a first state for inhibiting the flow of temperature controlfluid through the passageway and a second state for allowing the flow oftemperature control fluid through the passageway, the method comprisingthe steps of:receiving an engine temperature signal indicative of theengine block temperature; receiving a temperature control fluidtemperature signal indicative of the temperature control fluidtemperature; comparing the engine temperature signal to a predeterminedengine temperature value to determine a desired state of the flowcontrol valve; determining whether the flow control valve is in thedesired state; adjusting a predetermined temperature control fluidtemperature value based on the comparison of the engine temperaturesignal to the predetermined engine temperature value if the flow controlvalve is not in the desire state; comparing the temperature controlfluid temperature signal to the adjusted temperature control fluidtemperature value; and actuating the flow control valve into the desiredstate.
 28. A method according to claim 27 further comprising the stepsof sensing a temperature of the engine block and providing the enginetemperature signal indicative thereof, and sensing a temperature controlfluid temperature and providing the temperature control fluidtemperature signal indicative thereof.
 29. A method according to claim27 wherein the adjusting of the temperature control fluid temperaturecomprises the steps of:determining the amount that the enginetemperature signal exceeds the predetermined engine temperature value;determining an adjustment factor for adjusting the predeterminedtemperature control fluid temperature value based on the amount of saidexcess; and combining the adjustment factor and the predeterminedtemperature control fluid temperature value to form the adjustedtemperature control fluid temperature value.
 30. A method forcontrolling the temperature state of an internal combustion engine, theengine including a flow control valve for controlling flow oftemperature control fluid between a radiator and a passageway in theengine, the valve having a first state for inhibiting the flow oftemperature control fluid between the radiator and the passageway and asecond state for allowing the flow of temperature control fluid betweenthe radiator and the passageway, the flow of temperature control fluidbetween the radiator and the passageway providing cooling of the engine,the method comprising the steps of:receiving a first temperature signalindicative of the engine oil temperature; receiving a second temperaturesignal indicative of the temperature control fluid temperature; andmaintaining the first temperature signal substantially at apredetermined temperature value by actuating the flow control valve intoits second state when the first temperature signal is greater than thepredetermined temperature value and the second temperature signal isbelow a flow control valve actuation temperature and above a lowertemperature limit, and by actuating the flow control valve into itsfirst state when the temperature signal is less than the predeterminedtemperature value and the second temperature signal is greater than theflow control valve actuation temperature and below an upper temperaturelimit.
 31. A method for controlling the temperature state of an internalcombustion engine, the engine including a flow control valve forcontrolling flow of temperature control fluid between a radiator and apassageway in the engine, the valve having a first state for inhibitingthe flow of temperature control fluid between the radiator and thepassageway and a second state for allowing the flow of temperaturecontrol fluid between the radiator and the passageway, the flow oftemperature control fluid between the radiator and the passagewayproviding cooling of the engine, the method comprising the stepsof:receiving a temperature signal indicative of the engine oiltemperature; selecting a threshold temperature value from a set oftemperature values defining a curve having at least a temperaturecomponent indicative of engine oil temperature; maintaining thetemperature signal substantially at the threshold temperature value byactuating the flow control valve into its second state when thetemperature signal is greater than the threshold temperature value, andby actuating the flow control valve into its first state when thetemperature signal is less than the threshold temperature value.
 32. Atemperature control system according to claim 1 wherein the enginecomputer compares the temperature control fluid temperature signal to afirst temperature limit when the engine oil temperature signal exceedsthe predetermined engine oil temperature value and the temperaturecontrol fluid temperature signal is less than the temperature controlfluid value.
 33. A temperature control system according to claim 32wherein the first temperature limit is in below 200° F.
 34. Atemperature control system according to claim 33 wherein the firsttemperature limit is about 170° F.
 35. A temperature control systemaccording to claim 1 wherein the engine computer compares thetemperature control fluid temperature signal to a second temperaturelimit when the engine oil temperature signal is below the predeterminedengine oil temperature value and the temperature control fluidtemperature signal is greater than the temperature control fluid value.36. A temperature control system according to claim 35 wherein the firsttemperature limit is above 200° F.
 37. A temperature control systemaccording to claim 36 wherein the first temperature limit is about 240°F.
 38. A temperature control system according to claim 10 wherein theadjusted temperature control fluid temperature value is not below about170° F.
 39. A temperature control system according to claim 10 whereinthe adjusted temperature control fluid temperature value is not aboveabout 240° F.
 40. A method according to claim 21 wherein the step ofactuating the flow control valve involves receiving a temperature signalindicative of the temperature control fluid temperature, comparing thetemperature control fluid temperature signal to an upper temperaturelimit if the first state is the desired state, and providing signals foractuating the flow control valve into the desired state if the firststate is the desired state and the temperature control fluid temperaturesignal is below the upper temperature limit.
 41. A method according toclaim 21 wherein the step of actuating the flow control valve involvesreceiving a temperature signal indicative of the temperature controlfluid temperature, comparing the temperature control fluid temperaturesignal to a lower temperature limit if the second state is the desiredstate, and providing signals for actuating the flow control valve intothe desired state if the second state is the desired state and thetemperature control fluid temperature signal is above the lowertemperature limit.
 42. A method according to claim 24 wherein theadjusted temperature control fluid temperature value is not below about170° F.
 43. A method according to claim 24 wherein the adjustedtemperature control fluid temperature value is not above about 240° F.